Smoke filling a Main Street building Wednesday morning was caused by fire in a commercial dryer, firefighters said.

A fire alarm was triggered shortly before 8:30 a.m. in the building at 139 Main St., and when firefighters arrived on the scene, they discovered smoke coming from the crawl space at the rear of the unit.

While searching for the source of the smoke, firefighters discovered towels burning in a dryer in the Washing Well at 140 Parker Harding Plaza, located on the opposite side of the structure.

The smoldering blaze was quickly extinguished, firefighters said.