DELAWARE, Ohio (AP) — Fire officials in central Ohio say five workers have been injured in a foundry explosion.

Officials say the fire at Liberty Casting Company, in Delaware, was already extinguished when crews responded to the scene around 10 p.m. Tuesday.

City of Delaware Fire Chief John Donahue says four people were taken to Ohio State University Wexner Medical Center and another person was airlifted to Grady Memorial Hospital. Donahue says the workers suffered burns, but their conditions weren’t known.

According to the company’s website, they specialize in "gray, ductile and high alloy iron casting."

No further details were immediately available. The cause of the explosion is under investigation.