(Updates with more details of 2011 inspection, number unaccounted for)
By Carey Gillam and Corrie MacLaggan
WEST, Texas, April 19 (Reuters) - Investigators searched for clues on Friday to the cause of a Texas fertilizer plant explosion that obliterated sections of a small town and killed at least 12 people, including volunteer firefighters who raced to the scene to douse a blaze.
There was no indication of foul play in the blast at West Fertilizer Co, a privately owned facility that authorities said had not been inspected in two years.
The farm supply business, located in a residential area of West, had told a state agency that it stored potentially combustible ammonium nitrate on the site.
A Texas state official said Friday that 12 people died in the blast and approximately 200 were injured. Earlier, the mayor of West said 14 had died.
Texas U.S. Senator John Cornyn said the deputy fire marshal of the town told him that 60 people were still unaccounted for but that number was expected to come down. Authorities are cross-referencing people who are at the hospital, maybe staying with relatives or have left town, he said.
“I would just take that (number) with a grain of caution,” Cornyn said.
The deaths included paramedics and volunteer firefighters who responded to an initial fire alarm, and likely were killed by the ensuing blast, which was so powerful it registered as a magnitude 2.1 earthquake.
It left a devastated landscape, reducing a 50-unit apartment complex to what one local official called “a skeleton standing up,” destroying about 50 homes and heavily damaging a nursing home and schools.
Officials on Friday said 25 homes had yet to be searched. In some cases the structures needed to be reinforced before anyone could enter, they said
The explosion was one of a series of events that put Americans on edge this week including the Boston marathon bombing and discovery of poisoned envelopes addressed to President Barack Obama and a Republican U.S. senator.
Authorities were still calling the blast site a crime scene though they said they strongly suspected an accident.
The death toll was huge for a town of 2,700, and nearly everyone seemed to know someone who died or was presumed dead.
Brian Uptmor, 37 said his brother disappeared after he went toward the fire on Wednesday night to try to save horses in a pasture near the plant.
William “Buck” Uptmor, 44, has not been found among the injured at area hospitals, has not answered his cell phone and his truck has not moved from where he left it.
“He is dead. We don’t know where his body is,” said Uptmor, a former firefighter. “It’ll probably hit me at the funeral.”
Residents of the town known for its Czech heritage gathered at the Out West Bar and Grill in downtown West on Thursday night, where some of the first responders who died in the blast used to drink beer with them.
“Everyone’s still shocked,” said 48-year-old Kenny Chudej, who listed the names of several people he said he knew had died in the explosion. “We lost a lot of good friends. I don’t think it has hit home yet. Having a drink or two helps level it out.”
West Mayor Tommy Muska has said four paramedics are among the dead, and that five volunteer firefighters are listed as missing and feared dead.
Cornyn and Texas U.S. Senator Ted Cruz, who visited the blast site on Friday, said they were shocked at the tangled wreckage of one fire truck.
Volunteers and truckloads of donations were arriving in West from around the state, providing food, clothing and household items for people who lost their residences and possessions.
“It hit close to home. I‘m still in shock,” said 34-year-old Jami Staggs, who came from Waco 20 miles (32 km) away to help set up a site where West residents could pick up donated items.
West Fertilizer Co is a retail facility that blends fertilizer and sells anhydrous ammonia and other chemical products to local farmers. It stored 270 tons of “extremely hazardous” ammonium nitrate, according to a report filed by the company with the state government.
Farmers use anhydrous ammonia as fertilizer to boost soil nitrogen levels and improve crop production.
The West plant is one of thousands of sites across rural America that stores and sells hazardous materials such as chemicals and fertilizer for agricultural use. Many are near residences and schools.
The plant was last inspected for safety in 2011, according to a Risk Management Plan filed with the federal Environmental Protection Agency.
The company, which has fewer than 10 employees, had provided no contingency plan to the EPA for a major explosion or fire at the site. It told the EPA in 2011 that a typical emergency scenario at the facility that holds anhydrous ammonia could result in a small release in gas form.
The EPA fined the firm $2,300 in 2006 for failing to implement a risk management plan.
The plant’s owner could not be reached for comment.
While authorities stressed it was still to early to speculate on the precise cause of the blast, a forensic sciences expert said investigators probably would consider at least two scenarios.
John Goodpaster, assistant professor and director of forensic sciences at Indiana University-Purdue University Indianapolis, said anhydrous ammonia is stored in liquid form but forms a vapor when mixed with air that can be explosive.
If enough heat is applied to a container of anhydrous ammonia, he said, “that container could become a bomb.”
A second possibility is that ammonium nitrate, which was stored at the facility, could have exploded, said Goodpaster. This was the cause of one of America’s worst industrial accidents. In 1947 ammonium nitrate detonated aboard a ship in a Texas City port, killing nearly 600 people. (Additional reporting by Lisa Maria Garza, Nick Carey, Anna Driver and Josh Schneyer; Writing by Greg McCune; Editing by Xavier Briand)