LA MESA (CNS) - A 63-year-old National City woman was killed and her two passengers injured in a single-vehicle rollover crash overnight on a freeway transition ramp in La Mesa, authorities said.

The crash happened about 11:15 p.m. Wednesday on the looping connector ramp from northbound State Route 125 to westbound Interstate 8, California Highway Patrol Officer Travis Garrow said.

"For reasons still under investigation, the driver of the (2007 Dodge Caliber) entered the transition road at an unsafe speed," Garrow said, and while trying to negotiate the sudden curve, the Dodge struck a concrete retaining wall and rolled.

"As a result, the driver of the Dodge suffered blunt force trauma and succumbed to her injuries on scene," the officer said.

The victim's name was not immediately released.

There were reports that witnesses kicked out the windshield of the overturned car to help rescue a front-seat passenger. The CHP identified him as a 39-year-old Lemon Grove resident. Firefighters rescued a back-seat passenger who was trapped in the wreckage. She was later identified by the CHP as a 54-year-old from San Diego.

Both passengers were taken to Sharp Memorial Hospital in San Diego with moderate to major injuries, Garrow said.

All three occupants of the car were wearing seat belts, and investigators do not suspect that drug or alcohol impairment was a factor in the crash, Garrow said.

The deadly accident closed the connector ramp for more than five hours, but it reopened about 4:45 a.m. Thursday.