Nearly two dozen people were injured in an El Segundo bus crash Monday morning.

A big rig was parked at 2310 Imperial Highway around 8:20 a.m., as the driver was unloading equipment from the vehicle, El Segundo Fire Chief Deena Lee told KTLA. The driver was standing in the No. 3 lane on the road, Lee said.

A Los Angeles Department of Transportation commuter bus with about 20 occupants was driving by at the time. The bus clipped the driver of the big rig, injuring him critically, Lee said.

The collision caused the bus driver to lose control and the vehicle overturned, according to El Segundo Fire.

Three people were transported to local trauma centers in critical condition. Two people were hospitalized with moderate injuries. Fifteen people had minor injuries, with two of them taken to the hospital.

Sky5 was overhead just before 9 a.m. as the commuter bus appeared flipped on its side and paramedics were responding to the scene.

All eastbound traffic lanes of Imperial Highway at Douglas Street were closed due to an injury traffic collision. All traffic lanes will remain closed for several hours, officials said just before 9 a.m.

Drivers were asked to avoid the area and take alternate routes. 

No further details were immediately available.