Emergency crews are on the scene of a massive explosion at a southeast Missouri aluminum plant.

The explosion and fire around 12:30 p.m. CT Tuesday sent a large plume of smoke above the Noranda Aluminum plant near the town of Marston in New Madrid County, about 170 miles south of St. Louis.

Noranda spokesman John Parker says the company has accounted for all employees. He says there were no fatalities or critical injuries. Some people suffered what appeared to be non-critical burns and smoke inhalation.

Parker called the blast a molten metal explosion in the cast house of the plant, which employs about 900 workers. He says 20 people were working in the area when the blast happened.

The cause of the explosion is under investigation.