WEST, Texas - President Barack Obama issued an emergency declaration for Texas on Friday to help the state cope with the fallout from a deadly fertilizer plant explosion.The order authorizes the Federal Emergency Management Agency to "identify, mobilize, and provide at its discretion, equipment and resources necessary to alleviate the impacts of the emergency."Twelve people were confirmed dead and approximately 200 injured after a fiery explosion at a Texas fertilizer plant late on Wednesday, a Texas state official said on Friday.Jason Reyes, a spokesman for the Texas Department of Public Safety, said the bodies were found mainly in the area of the plant explosion.On Thursday, officials had initially said the death toll was between 5 and 15. The mayor of the small town of West, Texas where the blast occurred, Tommy Muska, later said that 14 people died, including some paramedics. Investigators continued searching for clues on Friday to the cause of the explosion and inferno after an apparent industrial accident at a Texas fertilizer plant flattened sections of a small town.Dangerous materialsWest 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.Anhydrous ammonia is used by farmers as fertilizer to boost soil nitrogen levels and improve crop production.The West plant is one of thousands of sites across rural America that store and sell hazardous materials such as chemicals and fertilizer for agricultural use, many within close range of residences and schools. The company is privately owned and has fewer than 10 employees.The plant had not been inspected by state officials since 2006, when a complaint of an ammonia smell was resolved, said Zak Covar, executive director of the Texas Commission on Environmental Quality. State inspections are done only when there is a complaint, Covar said.The federal Environmental Protection Agency 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 you apply enough heat 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 ever industrial accidents in 1947, when ammonium nitrate detonated aboard a ship in a Texas City port, killing almost 600 people.Authorities said there was no indication of foul play in the blast at West Fertilizer Co, which they said had not been inspected since 2006, was storing potentially combustible ammonium nitrate and was located in a residential area.The deaths included paramedics and volunteer firefighters who rushed to the plant to put out an initial fire and likely were engulfed by the ensuing blast, which was so forceful 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 60 to 80 houses and heavily damaging a nursing home and schools.Everywhere in this town of 2,700 known for its Czech heritage, shocked residents mourned the loss of family and friends.Brian Uptmor, 37 said his brother disappeared after he went toward the fire on Wednesday night to try to save some horses at a pasture near the plant.William "Buck" Uptmor, 44, has not been found among the estimated 160 injured at area hospitals, he 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 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 earlier had said that among the known dead were four paramedics. Five volunteer firefighters are listed as missing and feared dead, he said.