LYNDEN, Wash. -- A historic building in the center of Lynden is a total loss following a three-alarm fire that roared through the structure Monday afternoon and continued to burn hours after the fire started.

Flames and smoke could be seen tearing through the top floor of the three-story Delft Square Mall, a 1920s building that housed a mix of shops on its first two floors, the local Chamber of Commerce told KIRO 7 Eyewitness News.

The fire erupted in the Whatcom County town at about 1 p.m. and moved quickly through the nearly block-long building. The blaze, which shot flames 20 feet into the air, collapsed the mall's roof at about 2:25 p.m. and showered the lower floors with flaming debris.

SLIDESHOW: Flames, Smoke In Downtown Lynden

VIDEO: 3-Alarm Fire Roars Through 1920s Building

Firefighters used long poles to break out all the lower windows, and in some cases, smashed antiques in an attempt to control the blaze. Eventually, concern over the structural integrity of the building caused firefighters to pullout and nothing could be done but to let the building burn, fire officials said.

A witness across the street from the building said people could be seen still eating in the Japanese restaurant on the building's second floor as flames poured from the floor above.

"Just three minutes after they got out, the windows just blew," said witness Krystal Thalen.

Firefighters said although enormous amounts of water had been poured on the fire, the old timber building continued to burn for hours.

About 10 businesses had offices in the building.