SPANISH FORK — An accident involving four cars at the mouth of Spanish Fork Canyon Tuesday afternoon closed U.S. 6 for nearly two hours and sent one woman to the hospital in critical condition.

The accident happened just before 2 p.m. Tuesday, when the driver of a pickup, that was pulling a trailer carrying two four-wheelers, fell asleep while heading west down the canyon. The truck collided head-on with a minivan driven by a 60-year-old woman.

After colliding with the van, the truck hit the front of a rental car being driven by awoman. A third vehicle struck the trailer and locked on until they came to a stop.

Utah Highway Patrol trooper Jered Taylor said the woman in the minivan appeared to suffer a broken vertebrae as well as a broken arm. She was taken by ambulance in critical condition to Mountain View Hospital in Payson. The woman was visiting from Canyon City, Colo. The woman driving the rental car and the driver of the pickuppick-up truck were both unharmed.