A head-on collision on Highway 101 near San Anselmo Road in Atascadero sent four people to the hospital early Friday. Alcohol was a factor, according to the CHP.

The incident began at 3:10 a.m. when David Camporverde, 22, of Paso Robles was driving a 1999 Honda Accord and entered the southbound lane of the freeway at the Highway 41 off-ramp driving in the wrong direction. One lane of the freeway was closed because of construction, leaving only the fast lane open, CHP Sgt. G.J. Eggers said.

Camporverde reached about 65 mph when he encountered a Greyhound commuter bus traveling southbound at 45 mph. The bus driver, Francisco Montalvo, 45, of Richmond, saw the Honda coming toward the Greyhound and tried to veer to the left, but the two vehicles crashed head-on just south of San Anselmo.

Camporverde suffered major injuries in the crash and was taken to Twin Cities Community Hospital in Templeton, where he was admitted and charged with driving while intoxicated, Eggers said.

Three passengers of the 38 in the bus were also taken to Twin Cities with minor injuries, mostly complaints of pain. They were treated and released.

The remaining passengers were taken by a van provided by Atascadero State Hospital to a Denny’s restaurant, where they were to be picked up by another Greyhound bus. The bus had originated from Oakland. It had previously stopped in Salinas, and its next stop was to be San Luis Obispo.

The southbound lane of the freeway was closed from the time of the collision to 7:30 a.m.

“The bus had to be towed away, and that was the biggest problem,” Eggers said.