A grand jury looking into the shooting deaths of two men during the aftermath of hurricane Katrina has indicted seven police officers, the U.S. district attorney's office said Thursday.

The seven were indicted on murder or attempted murder charges and have been given 24 hours by a judge to turn themselves in.

Reports arose last year that police had shot at least six contractors on the Danziger Bridge days after the storm hit New Orleans because they believed the people were looters.

Ronald Madison, a 40-year-old mentally disabled man, and James Barsett, 19, died in the shooting.

It was originally believed both men were killed in a shootout, but details were confused in the chaotic days following Katrina, which hit the city on Aug. 29, 2005.

The Danziger Bridge incident occurred six days after the hurricane.

Defence lawyers urged caution with regard to the case.

"As a wise man once said, a district attorney can get a grand jury to indict a ham sandwich," said Franz Zibilich, attorney for officer Robert Faulcon, who is charged with murder and attempted murder.

"They heard only one side of the story."

With files from the Associated Press