The fertilizer plant that exploded in West, Texas has a past of violations according to USA TODAY.
In 2006, West Chemical and Fertilizer was fined $2,300 for failing to update a risk management plan, poor employee training records, and no written policy for a maintenance program.
The Environmental Protection Agency (EPA) said the company later told them they corrected the deficiencies.
The EPA is monitoring the air quality in the area of the explosion that's now said to have killed more than 30 people.
Agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) and "National Response Team "are trying to determine the cause of the catastrophe.
The U.S. Chemical Safety Board also has a team of investigators along with the Occupational Safety and Health Administration (OSHA) on scene.
Texas Gov. Rick Perry is calling the deadly fertilizer plant explosion in his state "a truly nightmare scenario."
Authorities said earlier Thursday as many as 15 people are feared dead and more than 160 others were injured in the explosion that leveled homes and businesses in the farming community of West, Texas.
Perry emphasized during a Thursday morning news conference that much of the information about victims still is "very preliminary."
Explosions rocked a fertilizer plant in West, Texas, Wednesday evening as firefighters were battling a fire, causing multiple injuries, authorities said.
A hospital in nearby Waco reported receiving at least 45 patients.
"The injuries that we are seeing are very serious,'' said Glenn Robinson, CEO of Hillcrest Baptist Medical Center. "There are a number of patients that will be going to surgery.... It's a very, very unfortunate situation.''
Robinson said he did not know how many were in critical condition. He said helicopters were en route for more of the injured after earlier being grounded by high winds. And he said more patients were being taken to at least one other trauma center nearby.
Dani Moore, dispatcher with the Texas Department of Pubic Safety, said she did not know how many were injured or the extent of their injuries.
"The fertilizer plant was on fire. Firefighters were on the scene. There was an explosion ... followed by a second explosion,'' she said.
She said there were multiple damages to structures and vehicles. She said she had no information on the cause of the blasts or fire.
Waco Police Sgt. William Patrick Swanton told the AP early Thursday he doesn't know how many people have been rescued since the Wednesday night explosion in downtown West.
But he says officials on the ground remain in "search and rescue mode," going building to building in the largely decimated neighborhood surrounding the plant. He says he knows some firefighters still are missing.
WFAA.com reported at least 10 structures were on fire, including a school which is next door to the plant. An emergency triage center was set up at a high school football field.
The TV station said on its website that a shock wave was felt in parts of North Texas.
The Waco Tribune reported firefighters were among the injured.
The fertilizer plant is about 20 miles north of Waco and just off Interstate 35.
KWTX.com reported one of the nearby buildings damaged was a nursing home, and state troopers transported some of the injured to hospitals in patrol cars.
It also said the explosion knocked out electrical power to part of the community.
Of the first 45 patients to arrive at Hillcrest, 25 of them came by private vehicle and 20 by ambulance, Robinson said.
He said most of the injured appeared to have blast-caused injuries.
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