DENVER -- Insurance and fire investigators are trying to determine what caused an explosion that leveled a building near Breckenridge and injured a man.

The explosion destroyed the office at the Good Times Adventures lodge on Tiger Road.

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.

Brian Mislanski, an employee for the lodge, was inside the building at the time of the explosion and was buried up to his chest in rubble. He was listed as being in serious condition Sunday.

Firefighters were able to free him. Mislanski was conscious and alert, said Scott, and was airlifted to Denver by a flight for life helicopter.

The building that exploded was the main office, with an apartment upstairs, said Scott.

The adventure lodge offers dog sled and snow sled rides. One dog was reported missing, Scott said.