The westbound 101 Freeway remains closed in Agoura Hills Thursday morning, hours after a pair of crashes involving two semi trucks, at least one of which jackknifed, blocking the roadway.

The closure began shortly after 1:10 a.m., when two big rigs and a third vehicle collided on the freeway west of Chesebro Road, according to the California Highway Patrol.

The SigAlert will remain in place “until further notice,” the CHP added.

Footage from the scene shows that the trucks sustained major damage to their front ends, while the third vehicle, a dark-colored SUV, was on its passenger side in vegetation along the roadway.

At least one person could be seen as they were loaded into an ambulance, but their condition is unknown, as is that of others in the crash.

A woman at the scene told Key News Network that she witnessed the second collision when she stopped to help those involved in the first crash, which was between the SUV and one semi-truck.

“Another semi-truck came down the freeway and could not stop in time and went through the back end of the Amazon truck,” she said.

She added that she did not know how the first accident occurred.

Alexis Lewis contributed to this report.