An explosion rocked downtown Bozeman Thursday morning, collapsing three buildings and prompting evacuation of a two-block area, officials said.

Reports indicate the explosion happened at about 8:15 a.m. in the 200 block of Main Street.

Crews were working to extinguish a fire caused by the explosion.

Boodles restaurant and bar were destroyed, KBZK-TV reported. A police dispatcher said the adjacent Rocking R bar was also heavily damaged. Police evacuated the two blocks surrounding the businesses, housed in historic brick buildings.

Jason Shrauger with Gallatin County Disaster and Emergency Services said it was unknown what caused the explosion or if there were any injuries.

Witnesses reported seeing debris fly three times the height of the two-story building. Glass windows on downtown storefronts two blocks away were shattered by the blast, the Bozeman Daily Chronicle reported.

City officials were investigating the possibility that a natural gas leak caused the explosion, the Chronicle reported.

As of 10 a.m., no victims from the explosion had been admitted to Bozeman Deaconess Hospital, the city's primary medical facility, said hospital spokeswoman Keli Tondre.

The blast shook ceiling tiles at Schnee's Boots and Shoes three blocks from the explosion and knocked down shoes that were on display, but no one was hurt, said Dawn McClelland, who had just reported for work when the blast happened.

"The whole building shook," she said. "I thought somebody had rammed (a car) into the back of the building. The people up front thought the ceiling was falling in."

Two hours later, McClelland was preparing to leave as a haze hung over downtown. The store was closed for the day.

Ken Olson, the owner of the Pickle Barrel, a Main Street restaurant, said no one was in his eatery at the time of the explosion and he believes all of his employees are safe.