Markham fire crews battled a blaze that broke out in a historic building located in the Unionville Heritage Conservation District Wednesday afternoon.

The fire erupted at approximately 12:30 p.m. in the former Queen's Hotel on Main Street, near Carlton Road. Markham Fire Chief Bill Snowball said crews had a challenge getting the blaze under control.

"There's a lot of hidden spaces in there," he told CTV Toronto earlier on Wednesday. "We're trying to break through walls; there's three-foot gaps between walls -- just a very stubborn fire."

Built in 1860, the building is considered one of the oldest and most significant in the area.

"This is one of the most prominent commercial buildings on Main Street-Unionville," Markham's manager of heritage planning, Regan Hutcheson, said. "This is going to be a tremendous detriment for Main Street." The building's former owner, Dave Conway, was devastated about the loss.

"It's very sad," he said. "(The building) is what Unionville is all about."

The former hotel currently holds serveral retail stores and offices. All of the employees had left the building by the time fire crews arrived at the scene. No injuries have been reported.

The cause of the fire and the amount of damage to the building are not yet known.

With a report from CTV Toronto's Scott Lightfoot