A multiple vehicle accident at the Main Street underpass of Highway 99 has closed an off-ramp and snarled southbound traffic.

The southbound Highway 99 off-ramp at Main Street is closed as of 9:20 a.m., according to the California Highway Patrol.

Traffic is also backed up through southbound Lander Avenue, as many drivers are attempting to avoid the traffic jam by exiting Highway 99.

CHP states the accident was a big-rig versus vehicle. Reports from CHP say the big-rig exited southbound Highway 99 at Main Street with no brakes and went through the intersection at 7:28 a.m., colliding with the vehicles.

CHP said there was someone pinned in one vehicle at 7:30 a.m.

The accident involved the big rig, a white Cadillac sedan, and a green GMC Yukon. Tow trucks are currently removing the vehicles from the scene, but the CHP advises the closure may be "extended."