New Orleans — A rash of violence swept through New Orleans and Jefferson Parish this weekend, just as officials geared up for the start of the Carnival season and began putting the final touches on preparations for Super Bowl Sunday.

New Orleans police investigated two homicides and multiple shootings, including an incident where a man with a history of mental illness shot an officer in the leg. The Jefferson Parish Sheriff’s Office is investigating a serious stabbing on Kent Avenue in Metairie on Sunday and a minor stabbing in Harvey on Saturday.

Authorities have made arrests in the officer-involved shooting and in the Metairie stabbing.

Damon Jones, 41, was booked with aggravated battery, disturbing the peace and resisting arrest in the officer-involved shooting, which occurred after the officer investigated a disturbance call at an eastern New Orleans gas station.

In the Metairie stabbing, Jesus Morgan, 50, was booked with attempted second-degree murder after authorities say he stabbed an acquaintance multiple times in the side after an argument, puncturing the victim’s lung.

According to New Orleans police, the homicides were the result of separate double shootings Saturday.

Shaquille Cooper, 21, was killed at an illegal block party in the 1800 block of Conti Street around 8:35 p.m. Police say that as an officer drove up to investigate the party, shots rang out, and Cooper was found lying in the street with multiple gunshot wounds.

Another unidentified man was found with a gunshot wound to the neck and taken to a local hospital.

Police say that when Cooper was found, he was wearing an electronic monitoring bracelet on his ankle.

Earlier that day, Frederick Calvin, 22, was killed in a shooting in the 1900 block of Rapides Street in the St. Anthony neighborhood.

Police say that Calvin was walking with a 20-year-old friend around 8 p.m. when an unidentified man approached them and opened fire.

Calvin died later at a local hospital from his injuries, while the other victim’s condition was unknown.

New Orleans police also investigated additional nonfatal shootings on Merrill Street, Palmyra Street, Newton Street, South Dupre Street and Paris Avenue over the weekend.

The gun violence comes at a particularly sensitive time for New Orleans as national media attention begins to focus on the impending Super Bowl.

More importantly, the spike in violence, which also includes a high-profile quintuple shooting at the city’s Martin Luther King Jr. parade last week, comes after police and city officials have spent months touting plans to drive down violent crime using increased collaboration and a targeted focus on suspected offenders.

Police Superintendent Ronal Serpas repeatedly has expressed confidence that his department is getting a better handle on crime, and praised the hard work of his officers when he announced the arrest of a 15-year-old suspect in the MLK shootings.

He also has said that during Carnival season, his officers will be even more vigilant as they search out armed suspects on the streets. Based on Magistrate Court records reviewed on Monday, police booked five men with being illegally armed while on a parade route.

Spikes in violence can negatively affect the public’s perception of a police department’s effectiveness, in part due to the media attention they receive, said George Capowich, a Loyola University criminologist who has partnered with the NOPD to test violence reduction strategies in certain neighborhoods. He said that even if police are showing improvements statistically, it can be hard to convince the public of that because those most high-profile incidents stick in their collective memories.

However, he noted that often public gatherings, such as Mardi Gras or the Super Bowl, can lead to crime spikes because they make it easier for perpetrators to find their targets.

“There is a difference in how the public perceives whether something is working and what we see from the quantitative data,” Capowich said. “You have to be careful a little bit in how much you generalize when you see certain things.”

Capowich said a wide variety of crime reduction strategies are being tested in the city, such as the highly publicized “NOLA for Life” campaign, the creation of a new anti-gang task force and the work Capowich is doing in changing policing practices in certain neighborhoods.

Some of those efforts have had early success — Capowich’s work has contributed to a decrease in aggravated batteries and aggravated assaults in the French Quarter — but it’s still much too early to make any definitive judgements, he said.

Scientists have to determine if it’s the programs that are leading to improvements or just random chance.

“It is an incremental process that occurs over time,” Capowich said. “There are all sorts of different programs going on simultaneously. … It is a longer-term process to see sustained improvement.”

It’s unlikely that any one effort is going to foster massive change, he stressed, because crime is a complicated social issue with many components.

He noted that cities like New York and Chicago, which have seen large violent crime decreases, saw those changes over extended periods, and in some cases are experiencng a reversal of certain positive trends.

But, Capowich noted that the crime statistics for Mardi Gras 2012 showed improvements over the same numbers in 2011, and that could be a positive sign for the celebration this year.

“There are no magic bullets to solving social problems. We’re not going to find one thing that’s going to cut it in half,” Capowich said.