Firefighters battled a massive blaze that ripped through a three-story commercial building in downtown Los Angeles Wednesday evening. Flames ripped through the roof of the boarded-up building located near the intersection of Los Angeles and 3rd streets. The blaze erupted just after 7:30 p.m., according to the Los Angeles Fire Department. Smoke billowed from the building after most of the flames were extinguished an hour later. It is unclear what sparked the blaze. No injuries were immediately reported. About 135 firefighters battled the fire. The building was red-tagged. LAFD says an official knockdown won't be declared most likely until Thursday morning.