TOONE, Tenn. (AP) - An explosion and flash fire Tuesday at a plant that makes flares for the military injured six people, three of them critically, authorities said.

The explosion at Kilgore Flares Co. was reported just before noon, said Cris Hill, a dispatcher at the Hardeman County sheriff's office.

A Memphis hospital said three people were brought there in critical condition and a smaller hospital in Bolivar reported three people there in good condition.

County Mayor Willie Spencer, who was at the scene, said the fire apparently was contained to one building, which was heavily damaged.

"It could have been a lot worse," he said. "Any time you have an explosion ... you never know how many people are around."

As for the cause, Spencer said, "I don't think they have a clue."

An operator who answered the phone at the plant's facility about 75 miles northeast of Memphis said the company could not release any information.