Two people are dead after an animal feed processing plant in the US exploded into a fireball this morning.
The International Nutrition plant in Ohama blew up and partially collapsed with 38 people working inside.
Omaha authorities said two were killed and 10 others were seriously hurt. The others were all accounted for.
Search-and-rescue experts worked into thenight to stabilise the building. It was not immediately clear whether their work would continue tomorrow.
''We haven't cleared the building yet because of the significant risk to our people,'' Interim Omaha Fire Chief Bernie Kanger said.
Emergency crews were sent to a "structure fire with people possibly trapped" about 10am local time, Kanger said.
First assessments found a fire and structural collapse, along with numerous victims.
Minutes later, a second alarm was called and the incident was declared a "mass casualty event", he said.
The cause of the blast had not been determined, but Kanger said there were no hazardous chemicals at the plant.
The explosion knocked out the lights in the building and sent workers scrambling for safety.
Nate Lewis said he was on the first floor when he heard the blast. The building went dark, so the 21-year-old used light from his cellphone to make his way across the production floor and outside.
''I was a production line worker, although I don't know if I want to be that anymore,'' said Lewis, who's worked at International Nutrition for about four months.
Jamar White said he heard a loud crack and looked up to see the back wall of the building collapsing.
''I ran at least 150 feet (45m),'' White said. ''I ran far enough to make sure nothing else would keep falling.''
Afterward, White said, he could see inside the third floor of the building where at least two co-workers were screaming for help.
There plant sits in an industrial area of Nebraska's largest city.