An explosion at an International Nutrition animal feed plant in Omaha, Neb., killed two people and critically injured four others, according to authorities. The incident occurred Monday, Jan. 20 at approximately 10:00 a.m., reports CNN.

"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 inside the plant a the time. Of the injured people, 10 were sent to the hospital; four of them had critical injuries. Seven others declined medical treatment.

CNN reports that the plant has been cited for 35 OSHA violations in 40 years, including seven violations after the 2002 death of an 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.

An OSHA spokesman said that investigators were at the plant, but it was too early to determine the cause of the accident. Part of the building had collapsed as a result of the explosion.

Source: CNN