AIR7 flew over the scene, where debris was seen littered around the construction site at 14265 W. Van Nuys Boulevard.
Los Angeles Fire Department paramedics said four people were hurt in the blast, and two of them were taken to the hospital. The two other patients reportedly refused transport.
AIR7 video shows patients being loaded into ambulances at the scene.
All four people who were hurt are expected to be OK. Drivers are being asked to avoid the area.
It's unclear what caused the blast, but the fire department suspects it may have been a welding-related natural gas explosion.