A University of California, Davis, bus lies on its side Thursday after overturning on eastbound Highway 50 in West Sacramento, Calif. The bus carrying medical students and health workers overturned on a busy freeway interchange, injuring 20 people. No injuries were life-threatening.

West Sacramento, Calif. ? A university bus carrying medical students and health workers overturned on a busy freeway interchange Thursday, injuring 20 people and snarling rush-hour traffic around the state capital.

The victims were treated at Sacramento hospitals for injuries described as ranging from minor to moderate, including bruises and possible neck sprains, a California Highway Patrol spokesman said.

The University of California, Davis, bus crashed shortly before 9 a.m., Sgt. Evan Williams said. All five lanes were closed on the freeway, part of the downtown business portion of Interstate 80.

“The bus shook violently then tipped; that’s all I remember,” said Charity Onore, 23, who was headed to work at UC Davis Medical Center in Sacramento. “I’m a little sore but mostly scared.”

The shuttle bus was carrying 28 passengers, Williams said. Most were students and hospital employees, said Meagan Herda, 20, a student assistant in pediatrics.

The bus driver, 46-year-old Marcella Muhammad, told officers she was traveling about 63 mph when a car in the left lane cut in front of her. She turned the wheel to avoid a crash and the bus rode up on a guardrail and rolled, Williams said.

But CHP Officer Phil Gruidl said it appeared Muhammad failed to round a curve in the road.

“This curve is negotiated by thousands of cars daily and it’s not dangerous at all, so yes, this is unusual,” Gruidl said.