The Los Angeles Fire Department is investigating a fire in a commercial building in North Hollywood on Saturday.

The blaze in the 6800 block of Troost Avenue was knocked down just before 7 p.m. by more than 80 firefighters, who worked for an hour and 46 minutes to contain the flames, the LAFD said in an alert.

Shortly into the battle, the building’s roof collapsed, forcing firefighters to exit the structure, though no injuries were reported, the LAFD said.

The LAFD Arson team is on scene investigating “per protocol for a Greater Alarm fire,” and firefighters remained on scene Saturday night to extinguish any hot spots, the Fire Department said.