LOS ANGELES >> Nearly two dozen people suspected of being members and leaders of the violent Mara Salvatrucha street gang known as MS-13 were arrested Wednesday in the largest-ever law enforcement action in Los Angeles against the gang, authorities said.

The 21 suspects arrested Wednesday were among 44 defendants named in a sweeping anti-racketeering indictment, some of whom are already in jail, according to the U.S. attorney’s office.

The massive sweep capped a nearly three-year investigation involving federal, state and local law enforcement authorities.

“These cases constitute the largest crackdown of MS-13 ever conducted in Los Angeles,” said Acting United States Attorney Sandra R. Brown at a news conference in Los Angeles on Wednesday after the arrests.

She added that more than half of the suspects named in the indictment were in the country illegally, but U.S. Immigration and Customs Enforcement was not involved in the investigation.

“This has nothing to do with their immigration status,” said Los Angeles Police Chief Charlie Beck as he joined Brown and other members of the law enforcement community. “This has to do with their criminal status. I will add that many of the witnesses that allowed us to do this by their statements also have immigration issues.”

Those arrested by members of the Los Angeles Metropolitan Task Force on Violent Gangs include the former head of the entire gang in Los Angeles and 12 senior leaders of the gang, who led a majority of the gang’s cliques in the Los Angeles region, authorities said.

The high-ranking gang members had formed a de facto MS-13 leadership council, a committee that was needed because no one person was willing to take on the top role in light of ongoing scrutiny by law enforcement, authorities said.

The indictment charges three MS-13 members for killings they are accused of committing in connection with the gang’s activities.

One suspect, Carlos Alfredo Cardoza Lopez, 23, also known as “Little Boy,” faces a violent crime in aid of racketeering — or VICAR — murder charge for allegedly fatally shooting an innocent bystander on Aug. 15, 2015, inside the gang-controlled Little San Salvador Nightclub and Restaurant on North Western Avenue, officials said. A friend of the victim was also stabbed during the attack.

Two other suspected MS-13 members — Samuel Alexander Paredes Rivas, 39, known as “Blacky,” and Joffri Molina, 24, known as “Espia” — are also charged with murder.

Rivas is charged with murder in the death a man on Aug. 30, 2015, at a strip mall in Pacoima. Molina is charged with murder in the death of a man on Sept. 27, 2015, on a street in North Hollywood.

“This gang is responsible for murders — both of rival gangsters and innocent bystanders — as well as drug dealing and extortion in many communities in the Los Angeles area,” Brown said. “With thousands of members here in the Southland, the gang’s power is widespread, power which it maintains with severe acts of violence.”

The three people facing murder charges could face the death penalty if convicted, authorities said.

Beck said there were 800 documented MS-13 members in L.A.