New Orleans — Two brothers with ties to a 7th Ward street gang were captured after a four-day manhunt and charged with gunning down 20 people in a shooting rampage at a Mother’s Day second-line parade on Sunday. The victims, 19 shot and another trampled in the chaos, were collateral damage in the brothers’ ongoing gang war, authorities said.

Shawn Scott, 24, spit onto the sidewalk as police led him past a row of television cameras Thursday afternoon. His younger brother, 19-year-old Akein Scott, grinned and chatted in an Orleans Parish courtroom.

Both are facing decades in prison. The brothers, who lived together at a home in the 3600 block of South Roman Street, are charged with 20 counts of attempted second-degree murder: one count for each of the victims wounded during the shooting. Four others were booked as accomplices. A judge ordered both held on $10 million bonds.

The two are alleged members of a generations-old gang called the Frenchman and Derbigny Boys, named after an intersection three blocks from Sunday’s mass shooting. Police Superintendent Ronal Serpas said the shooting was part of a street feud, but declined to specify its motive or intended target.

Surveillance videos of the shooting show a crowd of hundreds gathered for a second-line parade at the intersection of North Villere and Frenchmen streets. One gunman steps off the curb, raises a black and silver pistol and fires indiscriminately. Some run away; others fall.

A witness identified Akein Scott as the gunman who opened fire on the crowd by picking his picture out of a photo lineup, according to court records.

But a detective noticed that several of the victims, seen in the video, were visible behind the gunman as he fired, according to court records.

Akein Scott allegedly told someone that he and his older brother plotted the attack together, according to details contained in an arrest warrant. He was the shooter in the video, he allegedly told the person, and his brother was firing from the other side of the street, not captured by the camera. That person cooperated, and told detectives what they’d heard.

A witness also picked the elder Scott’s photo from a lineup, according to court records.

Serpas joined Mayor Mitch Landrieu and District Attorney Leon Cannizzaro on Thursday at the intersection where the shooting occurred —“sacred ground,” they called it — to announce the arrests.

”We all came back here to make it clear that the culture of death and violence on the streets of New Orleans is unnatural. It’s unacceptable,” the mayor said.

The number of anonymous tips that poured in were an indication, Serpas said, that the city’s residents are tired of the blood on the streets, tired of living in the nation’s most murderous city.

“The rules of the game have changed on the streets of New Orleans,” Serpas said. Citizen cooperation sent a message to gangsters: “You can’t scare anybody anymore.”

Tips led 5th District police officers to the Scott brothers’ hideouts.

Akein Scott was arrested just after 10 p.m. Wednesday, holed up at a home on Kingsport Boulevard in eastern New Orleans, where authorities allege Bionca Hickerson, 22, lives.

Hickerson, along with her sister, Nakia Youngblood, 32, were both charged as accessories after the fact to attempted second-degree murder.

Hickerson’s attorney, Donita Brooks, said the women were related to the Scott brothers by marriage.

Two others —Justin Alexander, 19, and Brandy George, 28 — were booked with the same crime. Each was originally booked with obstruction of justice and accessory after the fact, though prosecutors conceded Thursday afternoon that the evidence supported only the lesser charge of accessory after the fact, which carries up to five years in prison.

Authorities said that Hickerson, Youngblood, Alexander and George were all in the Kingsport Boulevard home where Scott was captured, and they each allegedly knew he was the subject of a high-profile, city-wide manhunt.

New Orleans police officers and United States marshals then set up surveillance outside an apartment on Haynes Boulevard, where they believed Shawn Scott to be hiding. They spotted him leaving the apartment, and he “appeared to be headed out of the area,” according to a police report filed in court records.

As officers moved in, Shawn Scott ran. He threw a bag, allegedly holding individually packaged bags of drugs, a total of 5.5 grams of heroin and another 91 grams of cocaine, the police report says.

Officers caught him, then discovered he was both on parole and a wanted fugitive.

On April 19, less than a month before the shooting, an arrest warrant described what happened when a police officer tried to stop Shawn Scott’s Nissan near South Claiborne and Washington avenues.

He refused to pull over, and instead fled to the home on South Roman he shared with his brother. He got out of the car, with a gun in his hand, and ran, the warrant says.

Police searched the abandoned car and found 29 bags of heroin in the center console. He was not located, and a warrant was issued for his arrest.

Shawn Scott is on parole after serving time for a June 2008 conviction on a charge of possession with intent to distribute heroin. He was sentenced to eight years in prison, but released for good behavior in May 2011, according to the Louisiana Department of Corrections.

Shawn Scott was slated to be on supervised parole until December 2015. His rap sheet also includes other convictions for crack and heroin possession, and his driver’s license is suspended for a dozen unpaid traffic tickets. He is considered a four-time violent offender, potentially facing a life sentence without the possibility of parole.

Akein Scott, a former student at Miller-McCoy Academy, was convicted of simple battery last year for allegedly attacking another man. He also had a pending charge of being in possession of a firearm while in possession of a controlled dangerous substance, after police allegedly caught him in March sitting outside a 7th Ward corner store with a bag of heroin and a handgun with an extended magazine. He was arrested hours before his older brother.

The younger brother strode into Orleans Parish Magistrate Court on Thursday morning smiling.

Shawn Scott was less brazen when he took his turn before a judge Thursday evening. He stood silently, clutching his rolled-up paperwork in his shackled hands.

Prosecutors requested a $500,000 bail on each count, for a total of $10 million, for each brother.

Magistrate Judge Gerard Hansen set Akein Scott’s bail at $10 million, or $500,000 per count.

Commissioner Robert Blackburn repeated the same amount for Shawn Scott on Thursday evening, and tacked on an extra $91,000 for the various drug charges he’s now facing — two counts of possession with intent to distribute heroin, another possession with intent to distribute cocaine and possession of drug paraphernalia.

Blackburn set bail for the accused accessories at $10,000 Thursday afternoon.

Three of those injured in Sunday’s shooting remain in critical condition, including Deb Cotton, a Gambit reporter and advocate for second-line culture.

Gambit, with the Tipitina’s Foundation, United Way of Southeast Louisiana and Silence is Violence have organized a brass band concert to benefit the victims, scheduled for Thursday at Tipitina’s.

The Big 7 Social Aid and Pleasure Club, the host of the second line that was cut short on Sunday, has also scheduled a “re-do” parade for June 1.

Landrieu pledged to “reclaim” the intersection of North Villere and Frenchmen, starting by tearing down a long-blighted house nearby.

“We will not bow down,” the mayor promised.