MONTICELLO, Maine -- John Tivnan said he was sleeping in a motor home near the north side of an old potato house on Route 1 in Monticello when the south side of the building burst into flames about 11:15 p.m. Monday.

"People on scene had to wake me," Tivnan said on Wednesday morning.

The fire destroyed the two-story, 180-foot long structure built in 1956 and more than $500,000 worth of antique cars stored inside that belonged to building owner Al Weiner and his wife.

"It was a total loss," Weiner said on Wednesday from Florida, adding that they were unable to insure the old building.

Monticello and Bridgewater Fire Departments fought the blaze and were on site all night, Tivnan said. They could not be reached for comment Wednesday.

The structure housed the antique vehicles including a Rolls Royce and a BSA motorcycle, antique radio equipment and a medical marijuana growing business, said Tivnan, a retired master electrician who works for Weiner and often stays on site for building security.

Weiner is calling the fire a mystery because he said there were people present and all of a sudden the building was completely engulfed in flames.

"I am thinking something exploded because the whole building was engulfed," he said. "We are awaiting a report from the fire marshal."

The fire marshal's office did not respond to a request for comment.

According to Tivnan, he lost about $30,000 in electrical parts and equipment, not to mention all his tools.

Weiner was leasing a portion of the building to Luc Fournier, who owns Sea of Green Inc., a state licensed medical marijuana caregiver.

The building was recently partially renovated including replacing a portion of the foundation and a new roof, Weiner said.

Despite losing the entire structure and its contents, Weiner said that he is rebuilding at the site.

"We are going to turn it into a communication site," he said.