Five current and former New Orleans police officers were convicted Friday on federal charges stemming from the Danziger Bridge case, perhaps the most notorious of several instances of violent police misconduct in the aftermath of Hurricane Katrina, when the city was plunged into chaos and fear.

On Sept. 4, 2005, six days after the city flooded, a group of police, responding to a call that fellow officers had come under fire, rode to the bridge in a Budget rental truck and shot at the people walking on it, killing two and injuring four. Federal prosecutors alleged that the civilians were unarmed - and that the officers later took part in an elaborate cover-up.

Mayor Mitch Landrieu said the jury verdict closed "a dark chapter in our city's history."

But others wondered if the lingering bitterness over the case would taint efforts to reform a notoriously underperforming and corrupt department. Peter Scharf, a Tulane University criminologist, said the decision could hinder the ability of the federal government to effectively carry out reforms under a consent decree being hammered out between city officials and the U.S. Department of Justice.

"I think right now there is a fear among the police, and a sense of being attacked," Scharf said.

The six-week trial featured testimony from five other NOPD officers who had already pleaded guilty to charges of obstructing justice and covering up the incident.

Prosecutors alleged that four of the defendants-sergeants Kenneth Bowen and Robert Gisevius, and officers Robert Faulcon and Anthony Villavaso-fired on the Bartholomews, a family walking in search of food and supplies, killing 17-year-old family friend James Brissette and wounding four others.

Minutes later, police shot at two brothers, Lance and Ronald Madison, according to a Justice Department summary. Officer Faulcon shot the mentally disabled Ronald Madison in the back as he ran away, witnesses said. Bowen stomped and kicked him before he died, according to the summary.

Officers arrested a man named Lance Madison on the scene and charged him with eight counts of attempted murder of police officers. But they collected no guns.

Prosecutors alleged that the fifth suspect, Sgt. Arthur Kaufman, a homicide investigator, joined the other four in covering up the incident, inventing witnesses, holding a meeting with the suspects to help them get their stories straight, and saying that a gun from his house was evidence found at the scene.

The four officers who were on the bridge were convicted of civil rights violations and charges related to the cover-up. They face potential multiple life terms.

The jury was asked to determine whether the killings amounted to "murder," which, while not a formal charge, would have resulted in potentially tougher sentences under federal statutes. But jurors declined to do so.