Firefighters attacked a three-alarm blaze at 17 Commonwealth Ave. Thursday morning. According to the Fire Department's official Twitter feed, the event started in the fourth-floor ceiling of a five-story building at 9:18 a.m.. There were no reported injuries as of 10:30 a.m..

"Report is the fire is in the duct work in the 4th floor ceiling. Companies opening up the ceiling," said the department in a tweet.

Firefighters quickly ordered a second alarm once they realized the blaze extended into the building's walls. A third alarm was struck at 10 a.m.