BRECKENRIDGE, Colo. -- Insurance and fire investigators were examining the remains of a building Sunday to determine the cause of an explosion that leveled the two-story structure and injured a man.

Images: Explosion Destroys Lodge

Day hikers saw the explosion and called 911 around 11:20 a.m. Saturday, said Capt. Kimberly Scott of the White and Blue Fire Protection District. The hikers said they saw a mushroom-like cloud of smoke in the air, Scott said.

The man was in a second-story apartment in the building that housed Good Times Snowmobile Tours and was buried up to his chest in debris. Neil Rosenberger, a battalion chief with the Red, White and Blue Fire District, said it took about four hours to free the man.

Brian Holt, owner of the business that offers snowmobile and sled-dog tours, said Sunday that the man's name is Brian Mislanski. He worked for the Breckenridge-area business.

Mislanski was the only person in the building. He was flown to St. Anthony Central Hospital in Denver.

A hospital spokeswoman said Sunday that he was in critical condition

Fire district spokeswoman Kim Scott said it likely would take several days to determine what caused the explosion.

Holt told the Summit Daily News that Good Times Adventures closed March 30. He said Mislanski was house-sitting for the managers who live in the building's upstairs apartment.

No nearby buildings were affected. Holt's 140 sled dogs were in good condition.

Mislanski's dog was reportedly missing.