The door at Buffa’s Lounge swung open, and two gunmen barged in.

One wore a ski mask, the other a bandana.

“Get down, get down!” they barked.

One put a pistol to a patron’s head and swiped his wallet. The second gunman shoved the bartender, Arden Radosevic, 50, toward the cash register.

Radosevic pulled out a stack of bills as he averted his eyes from the gun pressed against his stomach.

“If I don’t see it, maybe it’s not there,” he said later.

No one was hurt in the audacious holdup, which remains unsolved two weeks after it occurred. But it traumatized the victims nonetheless, as such crimes often do. And it came on the heels of a year that saw a huge spike in armed robberies — from street-corner muggings to convenience-store holdups — even as murders ebbed to a historic low.

The surge in armed robberies helps explain a recent wave of unease over crime in New Orleans. While murders tend to grab more headlines, experts say armed robberies are the crime that often strikes the most fear into residents’ hearts, for they tend to be more common and random in nature.

In recent weeks, French Quarter residents have put signs in their windows warning tourists of danger, citizens have organized a crime rally and a well-known businessman launched an advertising campaign calling out Mayor Mitch Landrieu on crime.

New Orleans police brass, meanwhile, have been scrambling to show progress in stemming the tide of robberies.

The NOPD declined to provide a final count of armed robberies for 2014, but department statistics showed they increased by 38 percent in the year’s first nine months, compared to the same period in 2013. And the number of calls to report armed robberies in all of 2014 was 35 percent higher than in 2013, suggesting the increase in robberies in the first three quarters held steady in the fourth.

Given that there were 729 armed robberies over the first three quarters, the final tally for the year is expected to be about 1,000, compared with 744 in 2013.

Calls reporting armed robberies increased in every police district in the city, with the most dramatic spikes occurring in districts that include Bywater, the 9th Ward, Central City and the Garden District, among other neighborhoods.

Stickups occurred in a Wal-Mart in New Orleans East, at a hotel on St. Charles Avenue and on New Orleans’ most famous tourist drag, Bourbon Street.

According to criminologists, the increase could have many causes: decreased police presence, demographic shifts, disruptions in criminal enterprises such as gangs or even a spree by a handful of robbers.

The Police Department has said that despite its depleted numbers — the number of commissioned officers has fallen by about a quarter since 2010 — a new task force is making inroads at combating stickups, among other violent crimes.

In addition, in many districts, the department reported arrest rates for armed robberies in 2014 that are in line with or above the national average — a statistic that appears to have done little to allay residents’ fears.

Armed robbery, according to criminologists, is a crime of opportunism. It is hard to solve, often involves repeat offenders and can create a climate of fear among residents, who worry that around any bend, a gun-toting man could be waiting for them.

Finding soft targets

There are four types of armed robbers, according to Edward Shihadeh, an LSU criminologist.

At the top of the food chain are the professionals, who pull off lucrative heists, such as bank robberies, with detailed plans. Next are the opportunists, low-level criminals who typically make impulsive decisions to hold up convenience stores or pedestrians as a way to get money. The bottom tiers are composed of drug addicts, who rob to feed their addictions, and alcoholics, who rarely have a plan to rob someone but do so spontaneously when under the influence.

Shihadeh said opportunists pull off the vast majority of holdups, and they would likely be the group responsible for the boost in armed robberies in New Orleans.

These are typically young people who cut their teeth committing simple thefts or burglaries; they also may be involved in the drug trade. They rob both for the thrill and for the income, and they aren’t particularly sophisticated about how they go about it.

“These are people who are too young, too inept and frankly too stupid to do anything else,” Shihadeh said.

Although many armed robberies may not be carefully planned, those who commit them are sensitive to who might make a soft target.

Peter Scharf, a criminologist at the LSU Health Sciences Center in New Orleans, said it’s commonplace for street muggings to occur in areas with high concentrations of tourists who may be flush with cash, are unlikely to be carrying a gun and often are unaware of their surroundings.

“Robbers are kind of like dinosaurs; they go where the grass grows,” Scharf said.

But contrary, perhaps, to popular opinion, armed robbery isn’t necessarily concentrated in areas frequented by out-of-towners.

There were 112 armed robberies last year in the 8th Police District, which includes the French Quarter and the Central Business District, an increase from 94 in 2013. That’s about the same number as in the city’s seven other districts.

A barrage of armed robberies committed in quick succession Uptown earlier this month allegedly was the handiwork of a group of men who lived in nearby Central City and the Irish Channel. Police arrested four suspects — Morris Smith, 17; Taman Martin, 18; Darrell Quinn, 19; and Tevin Quinn, 20 — in the robberies, after a brief car chase and manhunt.

Police said they have now tied the four to at least eight stickups, a couple of auto thefts and a shooting during a botched armed robbery in a St. Charles Avenue park.

The foursome’s alleged spree, according to criminologists, points to another characteristic of armed robbers: If not caught, they will often strike over and over again.

According to Shihadeh, the uptick in armed robberies in New Orleans last year — a jump of about 250 crimes — could be the product of as few as 10 or 15 busy criminals.

Diagnosing the spike

What caused armed robberies to increase in New Orleans in 2014 is a matter of conjecture.

NOPD Deputy Superintendent Bob Bardy said he believes the increasing popularity of a scam in which robbery victims are lured to hotel rooms or other meeting places through online dating sites could account for some of the rise.

Criminologists say a shortage of cops on the street might send a signal to criminals that it’s open season for stickups.

“When the police are drawing back for any reason, that’s going to create an opportunity for robbery,” said Richard Rosenfeld, a criminologist at the University of Missouri.

Rosenfeld also said gentrification — certainly a force in New Orleans — could increase robbery rates by bringing more affluent and potentially less street-savvy residents into rougher neighborhoods, where they become targets.

The jump also could be the consequence of a disruption in “crime markets,” a term experts use to describe the panoply of illicit activity that generates income for criminals.

Scharf said that if, for example, police are able to disrupt drug-selling gangs, low-level dealers might try to make ends meet by switching to stickups.

Shihadeh believes the spike could be the unintended consequence of the city’s aggressive efforts to reduce the murder rate by busting up violent gangs. “When you tamp out these gangs, there may be a vacuum to create lost income,” he said.

Shihadeh said arresting armed robbers is more important than deterring them through greater police presence. In that respect, the NOPD appears to be doing relatively well, despite its depleted ranks.

Nationally, police departments in cities with between 250,000 and 500,000 people made arrests in 24 percent of robbery cases in 2013. The NOPD had exactly the same arrest rate.

It posted above-average arrest rates in the 5th and 6th districts, which had the biggest increases in armed robberies.

Lower rate than other cities

The national statistics include simple robberies, where a weapon isn’t used but either threatened or actual physical violence is present.

No data are available, nationally or locally, on conviction rates.

Bardy said he believes a 16-man task force created in December and expanded this month will curb armed robberies by putting officers in “hot spots” where criminals are especially active. He said help from the public, as well as from the NOPD’s reserve unit, also will be key to combating the trend.

While last year’s spike is worrisome, New Orleans’ rate of armed robberies is well below that of many other cities plagued with endemic poverty and high murder rates, according to FBI data.

For instance, in 2010, when New Orleans had the nation’s highest murder rate, it ranked No. 51 among 420 large cities for which armed robbery data were available.

It’s also worth noting that even amid the recent spike, New Orleans’ armed robbery rate has fallen steeply since its peak in the early 1990s, when the city routinely recorded more than 300 murders a year.

In 1995, more than 4,500 armed robberies were reported in New Orleans — nearly five times as many as the city saw last year.

Still, those stats haven’t seemed to allay New Orleanians’ fears.

On a Facebook group called Safer Quarter, members post descriptions of people they deem suspicious, and 8th District detectives chime in asking for help in locating suspects.

And though most of the victims of stickups are locals, robberies of visitors do occur — to the chagrin of the city’s lucrative tourist trade.

Gloria Alfred, a 20-year-old Lafayette resident, was held up on the seventh floor of the Blake Hotel in the 500 block of St. Charles Avenue in January while returning from a stroll to the ice machine to freshen up a drink.

“They told me they were crazy down here, but I didn’t think they were that crazy,” she said.

Leaving a mark

Shihadeh, the LSU criminologist, said armed robbery is a crime that can induce waves of fear in the populace. For some, it may be a greater concern than ending up on the wrong end of a bullet.

A 1993 Gallup poll found that 19 percent of respondents said they worried often about being murdered, but 26 percent feared getting mugged.

For those who are unlucky enough to be targeted, the scars can be permanent.

A man who was robbed with his girlfriend of their wallets and groceries in the recent Uptown spree said the event left him so shaken that he now looks out the window before getting out of the car.

The man spoke on the condition of anonymity because he was afraid for his safety.

Radosevic, the bartender robbed at Buffa’s, returned to the bar the next day, along with his co-workers who had been present during the crime.

Mia Martinez, 41, a kitchen worker who had a gun pointed at her during the holdup, lingered with patrons near the cigarette machine.

She said she was still “in shock” about what had happened. She took a cab home from work the night of the incident, she said, though she normally rides her bike.

Another employee, Adam Wheeler, wrote on Facebook that he plans to quit his job because of safety concerns and move his family to Salem, Massachusetts.

Radosevic was more measured in his response. The day after the robbery, he bellied up to the bar and played a game on a computer tablet, his Australian shepherd-pit bull mix, Sheena, perched on the stool next to him.

He noted that he’d never been robbed before in 30 years of bartending. But he was still struck by how helpless he felt in the moment.

“A guy might weigh 100 pounds, but when he has a gun, he’s 6-foot-10, 380,” he said.

Follow Dan Lawton on Twitter, @dlawton.