A grand jury has declined to bring criminal charges against anyone in the 2005 police blockade that kept hundreds from crossing the Mississippi River to safety after Hurricane Katrina flooded New Orleans, the district attorney's office said Wednesday.

Several hundred people claimed police from suburban Gretna prevented them from crossing as they tried to flee New Orleans on Sept. 1, three days after the storm hit and floodwaters inundated the city. One officer, Lawrence Vaughn, allegedly fired a shot during the confrontation.

But a New Orleans grand jury on Wednesday declined to indict Vaughn on a criminal charge, said Dalton Savwoir, a spokesman for District Attorney Eddie Jordan.

"It certainly is a day of vindication for the Gretna Police Department," Police Chief Arthur Lawson said.

Many of the evacuees, who had been stranded at the New Orleans convention center without food and water, said they were told to cross the bridge to be evacuated from the city, only to be forced to turn around upon reaching the other side.

Police later said they blocked the evacuees because there were no supplies or services for them on the other side of the river. Cars, but not pedestrians, were allowed to cross the bridge for safety reasons, Lawson said.

Lawson said one of his officers, whom he declined to identify, fired a shot in an effort to quell unrest among the evacuees. Some of the people in the crowd acted aggressively and threatened to throw one of the officers off the bridge, the chief said.

"The officer did not fire the shot at the crowd (or) over the crowd," Lawson said. "It was fired over his shoulder, over the side of the bridge, as a warning shot to try to calm the crowd down."

Franz Zibilich, a lawyer for the police department, questioned why Jordan's office waited more than a year to present the case to a grand jury.

"I don't know what this was about, but it was absolutely never a crime," Zibilich said. "You didn't need a grand jury to determine whether there was an illegal discharge of a firearm."

The case raised widespread allegations of racism and spurred two marches across the bridge by national civil rights organizations in the months after the hurricane.

Lawson suggested politics played a part in the investigation.

State Sen. Cleo Fields, D-Baton Rouge, and state Rep. Cedric Richmond, D-New Orleans, filed a lawsuit against the police department and city, accusing officers of using excessive force and violating evacuees' rights. That lawsuit is still pending.

"It has been made into a racial issue by certain individuals, but that's not what it was all about," Lawson said.

Fields did not immediately return a reporter's telephone call Wednesday.

The New Orleans chapter of the ACLU filed a public records request with Jordan's office, seeking copies of police reports and other documents linked to the probe of the blockade. Jordan's office refused to turn over the records, citing the ongoing investigation.

"We just wanted to see it investigated fully and see the criminal justice system respond," ACLU lawyer Katie Schwartzmann said.

(Copyright 2007 by The Associated Press. All Rights Reserved.)