Two men remained in critical but stable condition Monday in University Hospital, where they are being treated for burns suffered during the weekend.

Gary Ott, 31, Terra, Tooele County, received second- and third-degree burns over 60 percent of his body Saturday when fire erupted as he and another man, Mike Montana, Salt Lake City, were painting the inside of a water tank at Dugway Proving Ground.Kathy Whittaker, public affairs officer at the military post, told the Associated Press that the cause of the fire is unknown and an investigation will be conducted.

The fire started about 4:45 p.m. near the Carr Facility, one of several high-security areas on the post, where tests are conducted with highly toxic chemicals and biological organisms.

Montana was treated at the hospital and released.

The other burn victim, a Reno, Nev., man, suffered second- and third-degree burns burns over 15 percent of his body when he was caught in a grass fire at a vacant home in the 2900 block of Wall Avenue in Ogden.

Ogden Police Lt. Dave Reed said the fire was reported about 8:20 p.m. Saturday by a woman who witnessed the victim, his clothes on fire, crawling from the front yard.

Reed said the cause of the fire is under investigation, but an open pack of cigarettes and a book of matches were found at the scene.

The injured man was taken by ambulance to McKay-Dee Hospital, before being flown to the U.