Initial reports put the fatalities as high as 15, but later in the day, authorities backed away from any estimate after Wednesday night's explosion in West, a community north of Waco. The blast injured more than 150 others.
Rescuers continue to search through smoldering rubble, but there is concern that toxic fumes might do harm to the emergency crews in the blast zone.
"I can tell you that I saw homes that were burning. There were homes that had significant devastation, based on windows blown out, bricks pulled off, siding pulled off," said Sgt. William Swanton with the Waco Police Department. "Some homes were leveled. It was almost tornadic in effect. One home would be fine, but next to it there would be extreme devastation."
Dallas Fire-Rescue Capt. Kenny Harris was initially reported missing after the explosion, but according to West Mayor Mike Rawlings, he has died. He was off duty at the time, but he responded to the fire to help out.
The explosion at West Fertilizer was reported shortly before 8 p.m. Before the blast, there was a fire at the plant, and firefighters were at the scene working to get the blaze under control. Among those believed to be killed are members of a volunteer fire department, as well as a police officer.
City leaders estimated that the explosion wiped out a four-block area of town, destroying or damaging 75 to 100 homes, apartments and a nearby middle school.
The blast registered as a 2.1-magnitude seismic event with the U.S. Geological Survey. But seismologists say their sensors can only record the ground motion, and that people who felt the shockwave above ground actually experienced a much larger event. Witnesses who were blocks away said they were thrown in the air by the explosion. Authorities say a large swath of the town looks like a bomb hit it.
A nearby nursing home was being evacuated because of the fire when the explosion went off. The nursing home was heavily damaged by the blast.
"There were some people that were in wheelchairs, and then we had others that were just trapped in their rooms," said West resident William Burch.
Authorities set up a staging area on the local high school's football field, which was lit up with floodlights. President Barack Obama released a statement expressing condolences to the victims.
"A tight-knit community has been shaken, and good, hard-working people have lost their lives. I want to thank the first responders who worked tirelessly through the night to contain the situation and treat the wounded," the president said. "West is a town that many Texans hold near and dear to their hearts, and as residents continue to respond to this tragedy, they will have the support of the American people."
The president said that his administration is in close contact with state and local officials to make sure "there are no unmet needs."
The Texas National Guard was called in to assist with the emergency. Federal authorities arrived at the scene to help with the investigation. Investigators said at this time there's no indication of foul play.
The plant produces ammonium nitrate fertilizer -- the same chemical used in the Oklahoma City bombing. The company that runs the fertilizer plant was fined $10,000 last year for safety violations. The fine was reduced after the company took steps to improve safety at the plant.
Authorities believe that a fire at the plant may have caused the tanks to overheat, which sparked the explosion. There's no word yet on what caused the initial fire.