GARNER, N.C. (AP) -- Two people were missing and 21 injured, four critically, after an explosion at a Slim Jim meat products plant in North Carolina, officials said Tuesday.
Jeffrey Hammerstein, district chief with Wake County Emergency Medical Services, said a third person initially reported missing was found and taken to the hospital. Authorities were searching for two others.
"We don't know if they're in the building or not, but we're going to go look for them," Hammerstein said.
Chris Woods, a worker at the facility, said he started running after feeling an explosion around 11 a.m.
"I was picking up a piece of meat off the line and I felt it, the percussion in my chest," Woods said. "One of the guys I was working with got blown back, he flew backwards."
Woods said he later saw people with burns on stretchers.
Hammerstein said five injured people were tagged as priority patients with serious conditions. Garner Mayor Ronnie Williams said injuries ranged from burns to smoke inhalation. Emergency crews were keeping people away because of concerns about ammonia, and Williams said there was a toxic cloud around the facility.
Patients were sent to five area hospitals. Four people were in critical condition at UNC Hospitals with burns covering between 40 and 60 percent of their bodies, said Dr. Charles Cairns, professor and chairman of the department of emergency medicine at the University of North Carolina.
"Anything that covers more than 50 percent of the body surface area is a very major burn and can be complex to take care of and can result in major complications, including death," Cairns said. "So these people are very severely burned."
About 300 people were in the plant a few miles south of Raleigh when the explosion happened, said ConAgra spokesman Dave Jackson. Parts of the roof collapsed.
Officials said firefighters were still trying to contain a small fire and an ammonia leak several hours later.
About 900 people covering four shifts work at the 50,000-square foot plant, which produces Slim Jim products and is considered one of ConAgra's largest, said Jackson, the spokesman for the Omaha, Neb.-based company.
"Obviously our first priority is the safety of our employees and the community and making sure our employees are accounted for and working with them to get them whatever they might need," he said.
ConAgra was sending a team of experts to the facility and helping local authorities.
ConAgra Foods Inc. makes brands like Chef Boyardee, Hunt's tomato sauce, ACT II popcorn and Hebrew National hot dogs. It has 25,000 employees worldwide.
The plant last was inspected by the North Carolina Department of Labor for workplace safety last July and no violations were found, said Labor Department spokeswoman Dolores Quesenberry.
Associated Press Writer Mike Baker in Raleigh and AP Food Industry Writer Emily Fredrix in Milwaukee, Wis., contributed to this report.