A van ferrying firefighters from Oregon to Colorado's worst wildfire in history swerved off a highway and spun out of control, killing four and injuring seven others.

The passenger van was carrying 11 members of a crew from Grayback Forestry to the 137,000-acre fire southwest of Denver on Friday when it drifted toward the median near Parachute, 170 miles west of Denver.

The Colorado State Patrol said the driver apparently overcorrected, swerved off the highway, and the van rolled four times and landed in a ditch.

The deaths were the first of the firefighting season in Colorado, a season that already has seen about 250 homes consumed by raging flames and more than 220,000 acres scorched by major fires still out of control.

Colorado State Patrol spokesman Don Moseman said the van was part of an eight-vehicle convoy heading to Colorado from La Grande, Ore., in the northeastern part of the state. Most of the people in the van were from Oregon and Idaho.

Moseman said other firefighters and support personnel in the convoy remained in the area, while others continued on to the fire. He wasn't sure how many people stayed behind.

"We had a lot of distraught people out there," Moseman said. "The vehicle was very heavily damaged. Of course in a convoy, some of their group saw it happen. It was very rough for them."

Retha Shirley, 19, from Baker City, Ore., was killed in the accident, authorities said. The names of the three other victims were not immediate released.

Moseman said reckless driving charges were possible against the driver, Megan Helm, 21, of La Grande, who had moderate injuries. There was no indication that alcohol or drugs were involved

Two passengers were listed in critical condition and another was in serious condition at St. Mary's Hospital in Grand Junction. Four others were being treated at Valley View Hospital in Glenwood Springs.

Oregon crews were on duty in 1994 when a tame 50-acre fire on Storm King Mountain outside Glenwood Springs in western Colorado blew up after a weather front moved through. Fourteen firefighters, including nine from the Prineville, Ore., Hot Shots, were killed as flames overwhelmed them.