Two civilians were injured Saturday when fire erupted as they painted the inside of a water tank in a high-security area of the Army post, a spokeswoman said.

Kathy Whittaker, public affairs officer for the post, identified the injured workers as Mike Montana of Salt Lake City and Gary Ott of Terra, Tooele County.Ott was in critical condition Saturday night in the Intermountain Burn Unit at University Hospital with burns over 60 percent of his body. Montana was treated and released at the hospital, a nursing supervisor said.

Both were employees of Blaine and Butcher Contractors.

Whittaker said the cause of the fire is unknown, and an investigation will be conducted. The blaze erupted about 4:45 p.m. near the Carr Facility, one of several high-security areas on the post, where scientists conduct tests with toxic chemicals and biological organisms.