Four other people were injured in the incident on the Danziger Bridge in the aftermath of Hurricane Katrina. Survivors say police officers ambushed and opened fire on unarmed men while police officials claimed there was a firefight on the bridge, The Times-Picayune newspaper in New Orleans reported Wednesday.

"As a result of this productive dialog and referral to us, the Civil Rights Division, FBI and our U.S. Attorney's Office will utilize as much time and resources as necessary to determine whether there are any prosecutable violations of federal criminal laws in this matter," Justice Department officials said in a statement.

Federal officials entered the case after Louisiana state district Judge Raymond Bigelow threw out an indictment of six current New Orleans police officers and one former officer on murder and attempted-murder charges in connection with the Danziger Bridge incident.

The New Orleans District Attorney's office is considering whether to appeal Bigelow's decision, The Times-Picayune reported.