WEST, Texas — Rescuers searched the smoking remnants of a Texas farm town Thursday for survivors of a fertilizer plant explosion, checking smashed houses and apartments for anyone still trapped in debris while the community awaited word on fatalities.
Initial reports put the death toll as high as 15, but later in the day, authorities backed away from any estimate and refused to elaborate. More than 160 people were hurt.
A breathtaking band of destruction extended for blocks around the West Fertilizer Co. in the small community of West. The blast shook the ground with the strength of a small earthquake and crumpled dozens of homes, an apartment complex, a school, and a nursing home. Its dull boom could be heard dozens of miles away from West, which is about 20 miles north of Waco.
Waco police Sergeant William Patrick Swanton described ongoing search-and-rescue efforts as ‘‘tedious and time-consuming,’’ noting that crews had to shore up much of the wreckage before going in.
There was no indication the blast, which sent up a mushroom-shaped plume of smoke and left behind a crater, was anything other than an industrial accident, he said.
The explosion was apparently touched off by a fire, but there was no indication what sparked the blaze. The company had been cited by regulators for what appeared to be minor safety and permitting violations over the past decade.
The Wednesday night explosion rained burning embers and debris down on terrified residents.
While the community tended to its deep wounds, investigators awaited clearance to enter the blast zone for clues to what set off the plant’s huge stockpile of volatile chemicals.
‘‘It’s still too hot to get in there,’’ said Franceska Perot, a spokeswoman for the Bureau of Alcohol, Tobacco, Firearms and Explosives.
The precise death toll was uncertain. Three to five volunteer firefighters initially were believed to be among the dead, which authorities said could number as many as 15. But the state Department of Public Safety later said the number of fatalities couldn’t be confirmed.
The Dallas Fire-Rescue Department said one of its off-duty firefighters, Captain Kenny Harris, was among those killed. Harris, 52, lived in West and had decided to lend a hand to volunteers battling the blaze.
Injuries included broken bones, cuts, respiratory problems, and minor burns. A few people were reported in intensive care, with several in critical condition.
First responders evacuated 133 patients from the nursing home.
William Burch and his wife entered the damaged nursing home before first responders arrived. They found residents in wheelchairs trapped in their rooms. The halls were dark, and the ceilings had collapsed.
Governor Rick Perry called the explosion ‘‘a truly nightmare scenario for the community’’ and said he had been in touch with President Obama, who promised his administration’s assistance with operations on the ground.
Authorities said the plant handles both the fertilizers anhydrous ammonia and ammonium nitrate, the latter of which was used in the 1995 Oklahoma City bombing .
Ammonium nitrate makes big explosions, be they accidental or intentional, said Neil Donahue, chemistry professor at Carnegie Mellon University. It is stable, but if its components are heated sufficiently, they break apart in a runaway explosive chemical reaction, he said.
About a half-hour before the blast, the town’s volunteer firefighters had responded to a call at the plant, Swanton said. They realized the potential for disaster because of the plant’s chemical stockpile and began evacuating the area.
The US Chemical Safety Board was deploying a large investigation team to West.
Records reviewed by the Associated Press show the US Pipeline and Hazardous Materials Safety Administration fined West Fertilizer $10,000 last summer for safety violations that included planning to transport anhydrous ammonia without a security plan.
In a risk-management plan filed with the Environmental Protection Agency about a year earlier, the company said it was not handling flammable materials and did not have sprinklers, water-deluge systems, blast walls, fire walls, or other safety mechanisms at the plant.
Texas require all facilities that handle anhydrous ammonia to have sprinklers and other safety measures because it is flammable, said Mike Wilson, of the Texas Commission on Environmental Quality.