NEW ORLEANS—U.S. prosecutors Tuesday charged six current or former police officers in connection with shootings on a bridge in New Orleans that left two dead and four wounded in the chaotic aftermath of Hurricane Katrina.

Victims and witnesses accused the police of firing indiscriminately and without warning on civilians on the Danziger Bridge in New Orleans on Sept. 4, 2005. Officers initially claimed the shootings were justified because they were fired upon, but federal prosecutors said the officers were not in danger and the civilians were not armed.

The racially charged case has become perhaps the most vivid and painful example of the confusion and lawlessness that pervaded the city after the storm. Most of the officers involved are white; the victims on the bridge were mostly black.

The case is one of several from the Katrina aftermath that have remained under investigation as the city nears the fifth anniversary of the storm. A state prosecution of the officers collapsed.

Attorney General Eric Holder, appearing at a press conference in New Orleans, said the unsolved cases arising from Katrina were among the first things he inquired about when he took office in 2009. "We will not tolerate wrongdoing by those who have sworn to protect the public," he said.