(CNN) — At least two people died and four were critically injured Monday in a plant accident in Omaha, Nebraska, authorities said.
The incident happened about 10 a.m. CT at International Nutrition, a company that produces feed and other products for livestock and poultry.
“I heard the explosion and stuff started falling, so I ducked for cover,” worker Nate Lewis told CNN affiliate KETV. “It was pitch black in there. All I could see was fire. I had to feel my way out of the place. I couldn’t see anything.”
There were 38 people at the plant at the time of the incident, interim Omaha fire chief Bernard Kanger said. Ten of the injured people needed a trip to the hospital, the chief said, adding that four were initially in critical condition.
Seven other people at the scene refused treatment, he said.
The mayor’s office and the county attorney’s office said two people had died. A spokeswoman for Mayor Jim Suttle said all other people at the plant were accounted for as of Monday night.
An employee told KETV that he heard noises, saw fire and sprinted for his life.
“I just heard a crack pop and big ball of fire, and I just took off running when I heard the first crack,” worker Jamar White “That’s all I could do was get out of the way and make sure I was OK.”
A spokesman for the Occupational Safety and Health Administration said OSHA investigators were at the plant, where part of the building had collapsed. Scott Allen said it is too early to determine the cause of the accident.
According to OSHA records obtained by CNN, International Nutrition Inc. has been cited for 35 OSHA violations over the past 40 years — most notably for seven violations following the August 20, 2002, death of a 45-year-old male employee who fell into a mixing tank and was mutilated by an auger.
International Nutrition also was fined $10,000 by OSHA in 2013 after a lengthy investigation found six violations, including two related to electrical safety standards for machines that were undergoing maintenance, Allen said.
International Nutrition isn’t on OSHA’s Severe Violator Enforcement Program, a list of companies that have knowingly disregarded safety regulations.
Authorities said the plant structure was unstable after the accident, which delayed recovery efforts.
“Because of the significant collapse and potential risk to our individuals, we had to pull everybody out of the structure and we have to call in specialized teams that can secure and shore up the building in order to allow us to completely clear the structure and declare that we’ve found all of the individuals that may have been in the building at the time of this incident,” Kanger said.
An urban search-and-rescue task force was activated by Nebraska Emergency Management.