FULLERTON (CBS) — Firefighters Wednesday will investigate the cause of a three-alarm fire that gutted a two-story building at the corner of Imperial Highway and Harbor Boulevard.

The blaze started at 10:30 p.m. Tuesday and became caught in the facade of the structure, which caused the roof to collapse, according to Fullerton Fire Department Div. Chief Julie Kunze.

The building located at 251 East Imperial Highway housed 17 units, including a dental office and a clothing distributor.

Several fire agencies were dispatched to the scene, including Orange County, La Habra, Brea and Fullerton. It took fire crews four hours and 15 minutes to extinguish the blaze.

“We still have several units on scene to put out hot spots. Other than that, we’re just waiting for the building to cool off and to get some equipment in here to start our investigation,” Kunze said.