NEW ORLEANS — Fifteen alleged gang members have taken up authorities’ offers of social services created to remove them from a life of crime, Mayor Mitch Landrieu said Tuesday.

That announcement came after local, state and federal officials held their third “call-in” session, an intervention with people on probation or behind bars for some of the city’s most violent crimes.

Landrieu said the message to those who gathered inside a courtroom at Orleans Parish Criminal District Court was the same as it has been during the last two meetings: Obey the law and accept the help that is offered or face the “swift” and “severe” consequences of your illegal actions.

Authorities met with 23 people, among 649 people who are reportedly involved with 39 gangs in the city. Tuesday’s session might have had more of an effect on the participants than the last two, said Police Superintendent Ronal Serpas.

Less than a week ago a grand jury handed up a 51-count indictment against 15 alleged members of the 110’ers, a gang whose members are accused of committing 15 murders in the last half-decade. Meanwhile, police continued their search for 19-year-old Akein Scott, the man accused of opening fire on a Mother’s Day second-line parade and injuring 19 people. Scott was identified a little more than 24 hours after that incident, Serpas pointed out.

“There was a fact in front of them about what can happen when we come together and work as a team,” Serpas said.

The call-ins are part of the NOLA for Life murder-reduction program and include the Multi-Agency Gang Unit. That group includes the New Orleans Police Department, Orleans Parish District Attorney’s Office, Orleans Parish Sheriff’s Office, U.S. Attorney’s Office and FBI.

The sessions are a group violence-reduction strategy, pioneered by criminologist David Kennedy, that is designed to address the relatively small number of people who authorities say are responsible for the majority of the murders in the city.

Social services offered are jobs and education, housing and mental health and substance abuse support. “They have a choice,” Landrieu said. “We are not going to tolerate violence any longer.”