The massive blast, which sent flames shooting into the sky and rained burning embers, shrapnel and other debris, occurred on Wednesday evening about 30 minutes after firefighters had been called to battle a blaze at the West Fertilizer Co. plant in West, a community of 2,800 about 30 kilometres north of Waco.
The explosion happened just before 8 p.m. CT and could be heard as far away as Waxahachie, 70 kilometres to the north. Ground motion from the blast registered as a 2.1-magnitude earthquake, according to the U.S. Geological Survey.
Jason Reyes, a spokesman for the Texas Department of Public Safety, told reporters Thursday afternoon that there were "confirmed fatalities" but would not confirm earlier estimates that between five and 15 people were killed.
Reyes said that officials from different levels of government were working together to find people and said the effort is still considered a "search and rescue" operation.
Two local buildings have been set up as community assistance centres for the people affected by the blast, which devastated several buildings around the plant.
Texas Attorney General Greg Abbott praised the effort of first responders and said the "support that we got in responding to this challenge is as big as Texas itself."
Earlier in the day, Waco police Sgt. Patrick Swanton said that the blast levelled homes and businesses and left "massive devastation in the downtown West area."
Swanton said there are a number of missing people, including between three and five firefighters. A law enforcement officer, who is also a volunteer firefighter, was initially among the missing but was located at a hospital with serious injuries, he said.
Reyes wouldn't confirm those estimates at a news conference later in the day and declined to provide any specific information about firefighters.
Firm 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. Authorities themselves had trouble entering the heart of the blast zone. "It's still too hot to get in there," said Franceska Perot, a spokeswoman for the Bureau of Alcohol, Tobacco, Firearms and Explosives.
Swanton said that the concussion of the blast "literally destroyed homes" around the fertilizer plant. Some parts of a 50-unit apartment complex had been ripped open by the blast, he said, making it possible to see inside.
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Texas Gov. Rick Perry said 75 homes received minor to substantial damage. A school near the plant was also damaged and classes will be suspended until at least Monday.
"Last night was truly a nightmare scenario for that community," said Perry, who declared a disaster in the area after the blast.West Mayor Tommy Muska was among the firefighters, and he and his colleagues were working to evacuate the area around the plant when it exploded. Muska said it knocked off his fire helmet and blew out the doors and windows of his nearby home.
"I ask for your prayers," Muska said at a press conference early Thursday morning.
William Snider, who lives near West, said his best friend lives in the area around the plant.
"His house burnt down, he lost everything. He's been at his mother-in-law's house," Snider told CBC's Reshmi Nair.
"I went and got him this morning, brought him to my house, gave him my pickup truck, clothes, $500 cash – what I had on me. That's the way I helped him, but there's a lot of people [that] need help."
After the blast
Some witnesses compared the scene to that of 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.
In the hours after the blast, many of the town's residents wandered the dark and windy streets searching for shelter. Among them was Julie Zahirniako, who said she and her son, Anthony, had been playing at a school playground near the fertilizer plant when the explosion hit.
The blast threw her son 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."
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The town's volunteer firefighters had responded to a call and due to the plant's chemical stockpile, "they realized the seriousness of what they had," Swanton said.
The main fire was under control as of 11 p.m., but residents were urged to remain indoors because of the threat of new explosions or leaks of ammonia from the plant's ruins.
Swanton said several fires at the plant and nearby homes are still smouldering but there appears to be no concern about air quality.
"I can tell you there is nothing out of control there at this point, meaning there is no fire out of control, there is no chemical escape from the fertilizer plant that is out of control," he said.
Authorities are treating the area as a crime scene until they can determine whether it was an industrial accident, Swanton said.
"Nothing at this point indicates that we have criminal activity," he said. "However, we are not ruling that out."
Swanton also said that there had been a small amount of looting in the cordoned off area around the plant but could not say if anyone had been arrested. Residents who were evacuated from their homes when the fire first began have still not been allowed to return and the Red Cross has set up at the local community centre.
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Dozens of emergency vehicles were massed 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 floodlit football field that had been turned into a staging area.
Investigators sent to West
The U.S. Chemical Safety Board said it was deploying a large team of investigators to West. The ATF and the state fire marshal's office are probing the cause of the fire.
There were no immediate details available from police 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.
Federal regulators fined the company that operates the fertilizer plant $10,000 last summer for safety violations. But the government accepted $5,250 after the company took what it described as corrective actions.
Records reviewed by The Associated Press show that the U.S. Pipeline and Hazardous Materials Safety Administration determined that the West Fertilizer Co. planned to transport anhydrous ammonia without making or following a security plan. An inspector also found that the plant's ammonia tanks weren't properly labelled. It is not unusual for companies to negotiate lower fines with regulators.
When asked if he worried about the safety of the plant, area resident William Snider said it wasn't something he had considered.
"That plant's been there forever and three days – it's been a fixture of the town," Snider told CBC News.
"I drive by it 20 times a day, never think about it. It's a…horrific accident."