CEDAR HILL, Mo. (AP) _ A woman who was critically wounded Friday in an explosion at the fireworks plant where she works later gave birth a month early after being flown to a hospital for treatment of her burns.

The 31-year-old woman was hurt in a noontime explosion at the Sunset Fireworks Factory. Another worker, a 25-year-old woman, was also critically injured.

Both women suffered second- and third-degree burns over 50 percent of their bodies.

A hospital spokeswoman said the baby girl was in serious condition. It wasn't clear if her condition was the result of burns or because she was born premature.

The cause of the explosion remained under investigation.

The women were working with black powder used in the fireworks. The blast blew the roof off the building, but thick concrete walls kept it from spreading to other parts of the complex, officials said.