Firefighters needed just 20 minutes Wednesday morning to knock down a large outside blaze at a one-story commercial building in North Hollywood.

Crews responded at 2:21 a.m. to what was initially thought to be “heavy structural involvement” at 6661 Lankershim Blvd., said Los Angeles Fire Department spokesman Brian Humphrey.

But the blaze turned out to be mostly a large outside fire that 40 firefighters limited to a small section of the exterior wall of one of the businesses in the structure, Humphrey said.

No injuries were reported, and the cause of the fire was under investigation.

The location is La Fonda De Don Cuper, a Salvadoran restaurant.