ConAgra plant had previous safety violations

Five of eight inspections since 2003 found no violations.

In 2001, inspectors noted 34 violations, including guards for wall and floor openings. The company settled with the Occupational Safety and Health Administration by paying a $12,100 fine.

The 425,000-square-foot plant was formerly owned by Raleigh-based GoodMark Foods and is known for making Slim Jim beef jerky products.

ConAgra spokeswoman Stephanie Childs said the company has sent a team of experts from its Omaha, Neb., headquarters to the plant to help determine the cause of Tuesday's explosion.

"We are working very closely with the local authorities to investigate what was the cause of this accident," Childs said. "Our focus is on our employees, their safety and their well-being."

The U.S. Chemical Safety Board, an independent federal agency charged with investigating industrial chemical accidents, also dispatched a team of experts to Garner to review the incident.

Footage from Sky 5 showed several holes in the roof of the ConAgra plant following the explosion, and seven or eight cars were smashed under part of the front of the building, which had been blown outward.

Liquid could be seen flowing from pipes along the roof and inside the plant, but it was unclear whether that was water or ammonia.

ConAgra implemented its emergency plan immediately after the explosion, dumping the ammonia from lines in the plant into a settling pond, said Diana Kees, a spokeswoman for the state Department of Environment and Natural Resources.

The state Division of Air Quality and the EPA sent managers to the plant to ensure emergency response plans and protocols for storing hazardous materials were being followed, Kees said.

Raleigh Fire Department Capt. Ian Toms, coordinator of the hazmat team, said high levels of ammonia were detected inside the plant several hours after the explosion. Ammonia levels outside the plant were negligible, he said.

Viney Aneja, a professor of air quality and environmental technology at North Carolina State University, said ammonia is a caustic substance that causes eye and skin irritation. He said it could be neutralized easily with a mild acidic solution.