An eyewitness account from two San Francisco paramedics posted on an internet site for Emergency Medical Services specialists says, "Thousands of New Orleaners were prevented and prohibited from self-evacuating the city on foot."
"We shut down the bridge," Arthur Lawson, chief of the City of Gretna Police Department, confirmed to United Press International, adding that his jurisdiction had been "a closed and secure location" since before the storm hit.
"All our people had evacuated and we locked the city down," he said.
The bridge in question -- the Crescent City Connection -- is the major artery heading west out of New Orleans across the Mississippi River.
Lawson said that once the storm itself had passed Monday, police from Gretna City, Jefferson Parrish and the Louisiana State Crescent City Connection Police Department closed to foot traffic the three access points to the bridge closest to the West Bank of the river.
He added that the small town, which he called "a bedroom community" for the city of New Orleans, would have been overwhelmed by the influx.
"There was no food, water or shelter" in Gretna City, Lawson said. "We did not have the wherewithal to deal with these people.
"If we had opened the bridge, our city would have looked like New Orleans does now: looted, burned and pillaged."
But -- in an example of the chaos that continued to beset survivors of the storm long after it had passed -- even as Lawson's men were closing the bridge, authorities in New Orleans were telling people that it was only way out of the city.
"The only way people can leave the city of New Orleans is to get on (the) Crescent City Connection ... authorities said," reads a Tuesday morning posting on the Web site of the New Orleans Times-Picayune newspaper, which kept reporting through the storm and the ruinous flooding that followed.
Similar announcements appeared on the Web site of local radio station WDSU and other local news sources.
"Evidently, someone on the ground (in New Orleans) was telling people there was transport here, or food or shelter," said Lawson. "There wasn't."
"We were not contacted by anyone" about the instructions being given to survivors to use the bridge to get out of town, he said.
The two paramedics, who were trapped in the city while attending a convention, joined a group of people who had been turned out by the hotels that they were staying in on Wednesday. When the group attempted to get to the Superdome -- designated by city authorities as a shelter for those unable to evacuate -- they were turned away by the National Guard.
"Quite naturally, we asked ... 'What was our alternative?' The guards told us that that was our problem, and no, they did not have extra water to give to us.
"This would be the start of our numerous encounters with callous and hostile law enforcement."
As they made their way to the bridge in order to leave the city "armed Gretna sheriffs (sic) formed a line across the foot of the bridge. Before we were close enough to speak, they began firing their weapons over our heads."
Members of the group nonetheless approached the police lines, and "questioned why we couldn't cross the bridge ... They responded that the West Bank was not going to become New Orleans and there would be no Superdomes in their City.
"These were code words," the paramedics wrote, "for if you are poor and black, you are not crossing the Mississippi River and you were not getting out of New Orleans."
The authors say that during the course of that day, they saw "other families, individuals and groups make the same trip up the incline in an attempt to cross the bridge, only to be turned away. Some chased away with gunfire, others simply told no, others to be verbally berated and humiliated."
Efforts to contact the authors of the Internet posting were unsuccessful, but UPI was able to confirm that individuals with their names are employed as paramedics in San Francisco.
Lawson says that his officers "acted in the manner they were instructed to" and defends the order to close the bridge as "the right decision."
He said that in addition to his security concerns, an unmoored vessel on the river "raised the threat that it might crash into and breach the levee, which would have flooded Gretna."
He says that his officers did assist about 4000 people who "arrived at the doorstep of (Gretna City)" either by crossing the bridge before it was closed or approaching from another route.
"We commandeered public transit buses and we took them to higher and safer ground" at the junction of Interstate-10 and Causeway Boulevard where "there was food and shelter," he said.