A big-rig crash on the northbound 5 freeway is slowing traffic out of the Santa Clarita Valley and blocking the Parker Road off-ramp to Castaic while crews work to remove an overturned semi truck and clean up a spill on the road.

A Sigalert was issued shortly before 2 p.m., said Officer Josh Greengard with the California Highway Patrol.

The collision involved two big-rigs and at least one other car.

“One of the big-rigs is blocking multiple lanes,” said Greengard. “One of them is overturned.”

However, only the No. 4 lane and the Parker Rd. off-ramp are being closed at this time.

The lane closure is expected to last for two to three hours, Greengard said, because an overturned big-rig is hard to right due to it’s large size and weight.