New Orleans saw scenes of chaos in the days after Katrina

A US judge has thrown out charges of murder or attempted murder against seven New Orleans policemen involved in a shooting after Hurricane Katrina.

The police officers were accused of firing on unarmed people crossing a bridge during the chaos which followed the flooding of the city.

Two men died and four were wounded in the shooting on the Danziger Bridge.

The judge ruled that prosecutors had violated state law by divulging secret grand jury testimony to a witness.

Survivors of the shooting on 4 September 2005 have said that police officers fired at unarmed people crossing the bridge to get food at a grocery store.

Ronald Madison, a 40-year-old mentally disabled man, and James Brissette, 19, were shot and killed, and four other people were wounded.

While the police officers have acknowledged shooting at people on the bridge, they say they only did so after first coming under fire.

Investigators later revealed that at least some of the shooting was by residents trapped by floodwater trying to attract the attention of rescue parties.

Sgt Kenneth Bowen, Sgt Robert Gisevius Jr, Officer Anthony Villavaso II and former Officer Robert Faulcon Jr had each faced first-degree murder and attempted murder charges in the case.

Officer Mike Hunter Jr and Officer Robert Barrios had faced attempted first-degree murder charges, and Officer Ignatius Hills had faced attempted second-degree murder charges.

Officer Faulcon resigned from the police force while the others were assigned to desk duty after their indictment, the Associated Press reports.

District Judge Raymond Bigelow also ruled that prosecutors had wrongly instructed the grand jury, and that grand jury testimony by three of the officers was used against them improperly.