FITCHBURG (CBS) – There’s no word yet on what caused a four-alarm fire that gutted a strip mall in Fitchburg overnight.

Flames broke out in the complex on River Street around 11:30 p.m. Wednesday and quickly spread to the roof. Part of the building collapsed.

READ MORE: Breaking And Entering Suspect Arrested After Falling Through Ice In Mystic River

A section of the facade came down near a Fitchburg fire lieutenant and just missed hitting him.

No one was inside at the time and authorities say no one was hurt.

READ MORE: Man Shot A Blackstone Valley Mall

(Photo credit: Scott Laprade)

(Photo credit: Scott Laprade)

But, Fitchburg fire chief Kevin Roy said some hydrants were buried and others were frozen.

“The sprinkler system in this building has been shut down for a few weeks, it was frozen during the cold weather.  Some of the buildings in the strip mall were occupied. Some of them were not,” Roy told reporters.

MORE NEWS: 6 Hunters Rescued By Coast Guard In Barnstable

The only business in the strip mall currently open is Beamer’s Pub. The others are vacant.