A two-vehicle crash on Lakeville Highway on Wednesday morning drew five ambulances and a medical helicopter and shut down the highway for almost three hours, according to the CHP.

With 11 people involved and injuries ranging from major to minor, a swarm of firefighters, paramedics and CHP officers set up a triage effort on the highway.

Ten people in the crash were employees of the California Conservation Corps, CHP Officer Jon Sloat said.

They were traveling in a large crew truck, headed for a job at a west Marin County park.

The worst injured appeared to be the man who crashed into the corps' vehicle, according to a preliminary investigation.

Driver Carlos Garcia, 47, of Petaluma had to be cut free from his Ford F-150 truck by firefighters. Paramedics then prepared him for a helicopter flight to Santa Rosa Memorial Hospital.

Garcia was in critical condition Wednesday morning, a hospital spokeswoman said.

Seven others had moderate to minor injuries and were taken by ambulances to Memorial and to hospitals in Petaluma, Sonoma and Napa, Petaluma Fire Capt. Jude Prokop said.

The remaining three were treated at the scene. Prokop said the employees riding together had a variety of head, neck and back injuries.

"They were very lucky ... the people in the crew van were not more seriously injured, given the complications of the accident," Prokop said.

Lakeville Highway was closed between Stage Gulch Road and Old Lakeville Road Three from about 10:30 a.m. to 1:10 p.m. Traffic backed up extensively in both directions and travelers were directed to alternate routes.

Garcia was headed south on the two-lane highway at about 50 mph. Near Old Lakeville Road Two, his truck drifted over double yellow lines into the northbound lane, Sloat said.

Garcia collided with the conservation corps' Ford F-550, driven by John Goodwin, 43, of Cool in El Dorado County.

The impact knocked the larger vehicle onto its side. Garcia's truck blocked both lanes.

Firefighters responded from Petaluma, Lakeville, Wilmar, Cal Fire and Sonoma Valley departments.

The others injured were Matthew Hancock, 23, of Rio Linda; Richard Henry, 21, of Greenwood; Jorge Hernandez of Cool, whose age was unknown; Justin Brown, 21, of Morwalk; Rachel Baker, 22, of Greenwood and Garin Merrifield, 21, of Cool.

(You can reach Staff Writer Randi Rossmann at 521-5412 or randi.rossmann@pressdemocrat.com.)