The evacuation of the Superdome was suspended Thursday after shots were fired at a military helicopter, an ambulance official overseeing the operation said. No immediate injuries were reported.
"We have suspended operations until they gain control of the Superdome," said Richard Zeuschlag, head of Acadian Ambulance, which was handling the evacuation of sick and injured people from the Superdome.
He said that military would not fly out of the Superdome either because of the gunfire and that the National Guard told him that it was sending 100 military police officers to gain control.
"That's not enough," Zeuschlag. "We need a thousand."
He also said that during the night, when a medical evacuation helicopter tried to land at a hospital in the outlying town of Kenner, the pilot reported that 100 people were on the landing pad, and some of them had guns.
"He was frightened and would not land," Zeuschlag.
"The reports that we have heard out there is that there are basically gangs out there with weapons who are shooting at helicopters, who are shooting at people," Gloria Roemer of the Harris County, Texas, Office of Emergency Management told CBS Radio News.
New Orleans authorities decided to wait until daylight before resuming helicopter flights.
"That's going to put our operations behind about 5 or 6 hours," Roemer said. "It's a tragedy in every sense of the word."
Zeuschlag said medics were calling him and crying for help because they were so scared of people with guns at the Superdome.
Lt. Col. Pete Schneider of the Louisiana National Guard said the military — which was handling the evacuation of the able-bodied from the Superdome — had suspended operations, too, because fires set outside the arena were preventing buses from getting close enough to pick up people.
He said tens thousands of people started rushing out of other buildings when they saw buses pulling up and hoped to get on. But the immediate focus was on evacuating people from the Superdome, and the other refugees were left to mill around.
Meanwhile, the first caravan of buses with Superdome refugees arrived early Thursday at the Astrodome in Houston, where they'll be sheltered temporarily - possibly for a long time - as authorities and relief officials try to figure out how to help them, and hundreds of thousands of displaced persons from Hurricane Katrina.
As the buses rolled in, some Houston residents were in the parking lot holding signs welcoming their neighbors from Louisiana.
"We are here to let them know - just to welcome the refugees," said one Texan. "We are here to support them, we love them and welcome them to Houston and let them know that this is their home even though they are not home and that they are more than welcome to stay here with us."
The air-conditioned Texas stadium - abandoned by the Astros five years ago as an outmoded facility - looked pretty good to some of the New Orleans hurricane victims as they got off the bus.
"The storm wasn't nothing," said one. "It was worst the days after, the water rise - we didn't have no kind of water, until the day after the hurricane."
"The Astrodome," said a Red Cross worker on hand to greet the refugees, "is a better place than they have been in until today, I can tell you that much."
The slow exodus from the smelly and sweltering Superdome began Wednesday as bedraggled refugees boarded giant trucks and then buses for a trip to more comfortable surroundings in the Houston Astrodome.
People with physical problems were evacuated Wednesday morning, loaded into a variety of vehicles and taken to a triage center in Baton Rouge. The evacuation of the more able-bodied began later.
Almost everyone carried a plastic bag or bundled bedspread holding the few possessions they had left after Hurricane Katrina decimated their city. Some hobbled on walkers, canes and crutches; others inched forward on wheelchairs. Women led children and carried babies.
"I don't care where they're taking us. Anywhere is better than here," said James Caire, 49, who had been at the Superdome only about six hours.
With no air conditioning and little electricity, the heat and stench inside the Superdome were unbearable for the nearly 25,000 refugees housed there. As the water pressure dropped lower and lower, toilets backed up. The stink was so bad that many medical workers wore masks as they walked around.
Most refugees jammed onto concourses because the heat and stench inside the Superdome were unbearable. But the heat on the brown-brick concourse was horrendous. One man took a paper bag, rolled up the rim and wore it as a hat.
Dr. Kevin Stephens Sr., in charge of the special needs shelter at the dome, described the Superdome and a nearby arena as a health department's nightmare.
"These conditions are atrocious," he said. "We'll take trucks, planes, boats, anything else, I have to get these people out of here."
By mid-afternoon, medics were hauling people off one after another because of heat-related problems. Even as the evacuation was going on, people walked through waist-deep water to get to the Superdome.
Tempers flared in the crowd. One woman yelled: "You're just lying to us! You had us standing all day in this heat, and you're lying to us. You're not taking us anywhere!"
The officer yelled back, "Look, ma'am, do you think I'm in charge? Do you think I'm making decisions? I told you what they told me."
The Astrodome's schedule has been cleared through December for housing evacuees, said Kathy Walt, a spokeswoman for Texas Gov. Rick Perry. The building no longer is the home of a professional sports team - the Houston Astros left in 2000.
Cots and blankets for up to 25,000 people were being set up on the Astrodome's floor. Knowing that the people would arrive tired, frustrated and disheartened, shelter organizers began planning activities that might help take the evacuees' minds off their troubles, such as free trips to museums and amusement parks.
Organizers plan to use Astrodome kitchens and locker rooms to keep refugees fed and clean, but even though Houston will have the electricity and dry land New Orleans lacks - taking care of thousands at the Astrodome won't be an easy job.
"Obviously, locker rooms were made to handle baseball teams and football teams, not crowds of 20,000 to 25,000 people," says Shea Guinn, president of SMG Reliant Park, which operates both the Superdome and the Astrodome.