Robert Dubuc thought he'd get a head start on a busy day at his West Side bakery in St. Paul last Friday, but what he found stopped all plans indefinitely: A van-sized boulder had crashed into the back of his business.

"It looked like a bomb went off back there," Dubuc said Monday.

Dubuc's now shuttered and condemned business sits at 385 Wabasha St. S. at the foot of St. Paul's limestone bluffs, where city authorities say a rockslide this large is unusual. Ricardo Cervantes, director of the city's department of safety and inspections, said the boulder is about 20 feet long and 12 feet high.

"On occasion we're going to have some rocks come out of the bluffs, but typically it's not going to land on a structure, and typically they're not this large," Cervantes said.

Dubuc believes the boulder fell sometime between midnight and 2 a.m. Friday. He arrived at the bakery about 2:15 a.m. with an extern.

At first, the two smelled gas. Further investigation revealed that the boulder had smashed through one-third of a rear wall and roof, and bent a gas pipe to the bread oven. No one was hurt.

"It's hard to think clearly right now," said Dubuc, who opened his bakery in 2008. "My whole life is wrapped up in the bakery, and other people's lives." He said he wants to rebuild -- but not there.

Dubuc said he always knew there was the possibility of rockslides, but he never envisioned such damage. It's unclear what caused the boulder to fall, but Cervantes said the long winter may have weakened the boulder's hold in the bluff face.

"We understand that the bluff, like much of Mother Nature, is in change," Cervantes said.

Homes on top of the bluff were not compromised.

Dubuc was allowed back in for the first time on Monday. He gathered up some paperwork but left behind an expensive bread oven. He made sure to grab his 13-year-old sourdough starter.

"The longer it's alive, the more flavor it has," he said of the starter. "It takes time, and I really need to keep that going."

Chao Xiong • 612-270-4708 Follow Chao on Twitter: @ChaoStrib