WEST, Texas (AP) - Search and rescue operations continue after a massive explosion at a Texas fertiliser plant killed as many as 15 people and injured more than 160, shaking the ground with the strength of a small earthquake and levelling homes and businesses for blocks in every direction.
Rescuers searched rubble early on Thursday for survivors.
The explosion in downtown West, about 80 miles (130km) south of Dallas, could be heard dozens of miles away. It sent flames shooting into the night sky and rained burning embers, shrapnel and debris down on shocked and frightened residents.
"They are still getting injured folks out and they are evacuating people from their homes," Waco police Sergeant William Patrick Swanton said early on Thursday morning.
He added later, "At some point this will turn into a recovery operation, but at this point, we are still in search and rescue."
Sgt Swanton said officials went from building to building in the largely decimated area around the plant that exploded with the strength of a small earthquake in downtown West, a farming community about 20 miles north of Waco.
"They have not gotten to the point of no return where they don't think that there's anybody still alive," Sgt Swanton said. He did not know how many people had been rescued.
Sgt Swanton said authorities believe that between five and 15 people were killed in the blast, but stressed that it was an early estimate as search and rescue operations remain under way. There is no indication the blast was anything other than an industrial accident, he said.
Among those believe to be dead: A group of volunteer firefighters and a single law enforcement officer who responded to a fire call at the West Fertilizer Co about an hour before the blast. They remained unaccounted for early on Thursday morning.
The US Chemical Safety Board said it was deploying a large investigation team to West. An Alcohol, Tobacco and Firearms national response team that investigates all large fires and explosions also was coming in, bringing fire investigators, certified explosives specialists, chemists, canines and forensic specialists.
But entry to the blast site wasn't expected until later. "It's still too hot to get in there," said ATF spokeswoman Franceska Perot.
American Red Cross crews from across Texas also headed to the scene to help evacuated residents.
The explosion that struck around 8pm (9am Singapore time) levelled a four-block area around the plant that a member of the city council, Mr Al Vanek, said was "totally decimated".
The toll included 50 to 75 houses, an apartment complex with about 50 units that one state police officer said was reduced to "a skeleton," a middle school and the West Rest Haven Nursing Home, from which first-responders evacuated 133 patients, some in wheelchairs.
Other witnesses compared the scene to the 1995 Oklahoma City bombing, and authorities said the plant made materials similar to that used to fuel the bomb that tore apart that city's Murrah Federal Building.
Although authorities said it will be some time before they know the full extent of the loss of life, they put the number of those injured at more than 160 early on Thursday. West Mayor Tommy Muska told reporters that his city of about 2,800 residents needs "your prayers".
"We've got a lot of people who are hurt, and there's a lot of people, I'm sure, who aren't gonna be here tomorrow," Major Muska said. "We're gonna search for everybody. We're gonna make sure everybody's accounted for. That's the most important thing right now."
In the hours after the blast, many of the town's residents wandered the dark and windy streets searching for shelter. Among them was Ms Julie Zahirniako, who said she and her son, Anthony, had been playing at a school playground near the fertiliser plant when the explosion hit. She was walking the track, he was kicking a football.
The explosion threw her son 4 feet in the air, breaking his ribs. She said she saw people running from the nursing home and the roof of the school lifted into the air.
"The fire was so high," she said. "It was just as loud as it could be. The ground and everything was shaking."
The town's volunteer firefighters had responded to a call at the plant at 7.29pm, Sgt Swanton said. Due to the plant's chemical stockpile, "they realised the seriousness of what they had", he said.
Mayor Muska was among the firefighters, and he and his colleagues were working to evacuate the area around the plant when the blast followed about 20 minutes later. Mr Muska said it knocked off his fire helmet and blew out the doors and windows of his nearby home.
Dozens of emergency vehicles amassed at the scene in the hours after the blast, as fires continued to smoulder in the ruins of the plant and in several surrounding buildings. Aerial footage showed injured people being treated on the flood-lit football field that had been turned into a staging area.
City council member Vanek said first-responders treated victims at about half a dozen sites, and he saw several injured residents from the nursing home being treated at the community center. Sgt Swanton said the injured were being taken to hospitals in Waco and a triage centre at high school in nearby Abbott.
Dr Glenn A. Robinson, the chief executive of Hillcrest Baptist Medical Center in Waco, told the Waco Tribune-Herald the hospital had treated more than 100 people, including 14 who would likely be admitted, but that none had died. He said the injuries included cuts, broken bones and others expected from flying debris. The hospital has set up a hotline for families of the victims to get information, he said.
Dr Robinson told the paper that 30 people were also treated at Providence Hospital in Waco, and several others were sent to the burn unit at Parkland Memorial Hospital in Dallas. Two children were taken to McLane Children's Hospital in Temple, he said.
"We did get there and got that taken care of," Mayor Muska said of the nursing home evacuation.
Mr Erick Perez, 21, of West, was playing basketball at a nearby school when the fire started. He and his friends thought nothing of it at first, but about a half-hour later, the smoke changed color. The blast threw him, his nephew and others to the ground and showered the area with hot embers, shrapnel and debris.
"The explosion was like nothing I've ever seen before," Mr Perez said. "This town is hurt really bad."
Information was hard to come by in the hours after the blast, and entry into the town was slow-going as the roads were jammed with emergency vehicles rushing in to help. A spokeswoman for Texas Governor Rick Perry said the state sent personnel from several agencies to help, including the Texas Commission for Environmental Quality, the state's emergency management department and an incident management team. Also responding is the state's top urban search and rescue team, the state health department and mobile medical units.
Sgt Swanton said he had no details on the number of people who work at the plant, which was cited by the Texas Commission on Environmental Quality in 2006 for failing to obtain or to qualify for a permit. The agency acted after receiving a complaint in June of that year of a strong ammonia smell.
In 2001, an explosion at a chemical and fertilizer plant killed 31 people and injured more than 2,000 in Toulouse, France. The blast occurred in a hangar containing 300 tonnes of ammonium nitrate, which can be used for both fertiliser and explosives.
The explosion came 10 days after the Sept 11, 2001, terrorist attacks in the US, and raised fears at the time it was linked. A 2006 report blamed the blast on negligence.