WOODLAND (CBS13) — Authorities say four people have been taken to the hospital after a crash involving several vehicles along Interstate 5 in Woodland on Thursday morning.

Scene of the crash. (Credit: Woodland Fire Department)

The Woodland Fire Department says the crash happened along the southbound side of the freeway near County Road 102.

Exactly what led up to the crash is unclear, but at least two cars and one big rig were involved.

Heavy extrication was required after the crash, firefighters say. A total of six people were involved, but two were released on scene. The other four have been rushed to the hospital with moderate injuries, authorities say.

More from CBS Sacramento:

Only one lane of southbound I-5 is open due to the crash. Drivers should expect delays in the area.