New Orleans has reached settlements totalling $13.3m (£10.7m) in lawsuits over deadly police shootings following Hurricane Katrina.

Announcing the compensation on Monday, which also covered a fatal beating just before the storm in August 2005, the mayor, Mitch Landrieu, apologised to the victims’ families on behalf of the city.

“I am hoping that in some sense the strength of these families will help the city find peace in our future,” he said at an afternoon news conference attended by some relatives of the victims. He said the settlements were with 17 plaintiffs.

Sherrel Johnson, the mother of 17-year-old James Brissette, who died in the 4 September 2005 shootings on the Danziger Bridge, was among those present for Landrieu’s announcement. She said she “wholeheartedly” accepted his apology.

“Since that time, it has been an awful long and rough road. But me and my family got through it,” she said. Later, she added, “Now this is closure for me, and I can go forward ... because I know the old New Orleans does not exist anymore.”

A total of 20 current or former New Orleans police officers were charged in a series of justice department civil rights investigations following the hurricane. All but one of the cases centred on alleged police misconduct during the chaos that gripped the flooded city.

Eleven officers pleaded guilty to charges related to deadly shootings on a bridge less than a week after Katrina’s landfall. Officers shot and killed two unarmed people and wounded four others on the Danziger Bridge before engaging in a cover-up that included a planted gun, fabricated witness statements and falsified reports.

Brissette and Ronald Madison, a 40-year-old man with learning difficulties, died in the bridge shootings. Lance Madison, Ronald’s brother, was on the bridge that day and was initially arrested after being falsely accused of shooting at officers.

A federal judge who presided over a trial for five of the officers charged in the bridge shooting threw out their convictions in 2013. US District Judge Kurt Engelhardt said at least three government attorneys posted anonymous comments on a New Orleans newspaper’s website, creating a “carnival atmosphere” that “distorted and perverted” justice in the case.

Engelhardt ordered a new trial for the five officers, who ultimately pleaded guilty in April. Lawsuits over the bridge shootings had been placed on hold while the criminal cases were pending.

Five other officers were tried on charges related to the death of 31-year-old Henry Glover, who was fatally shot outside a strip mall before his body was burned.

Former officer Gregory McRae, who burned Glover’s body in a car, is the only officer whose conviction in the case still stands. McRae is serving a prison sentence of more than 11 years.

The officer who fatally shot Glover was convicted of manslaughter but was later acquitted by another jury after an appeals court awarded him a new trial.

Two former New Orleans police officers were convicted of charges stemming from the fatal beating of Raymond Robair, a 48-year-old handyman who died less than a month before Katrina struck.

Former officer Melvin Williams was sentenced to more than 21 years in prison for kicking Robair and beating him with a baton. Another former officer, Matthew Dean Moore, was sentenced to more than five years in prison for submitting a false report and lying to the FBI about the encounter.

Robair’s relatives sued the city and former police superintendent Eddie Compass. LaShonda Enclade, Robair’s daughter, attended the news conference. She said she forgives the city, but forgiving the officers involved is more difficult.

“The word forgive is a very, very, hard word ... I’m not going to say I can ever forgive them. It’s something to be worked on,” she said.