A 36-year-old Bakersfield woman and a 6-year-old girl were killed Friday night when the woman lost control of her vehicle, which was then hit by a big-rig truck, according to the Kern County Sheriff's Office.

Jamie Robertson was merging onto southbound Highway 99 from Rosedale Highway when she lost control of the 1995 red Ford Mustang she was driving, California Highway Patrol officials said. Dispatchers responded to the emergency call at 8:08 p.m.

Merging in front of the 2010 Freightliner at a speed CHP officials said was "greater than reasonable" for Friday's cloudy and wet conditions, Robertson's vehicle was hit on the left side by the truck driven by Michael David Costa, 51, of Chowchilla.

When Robertson's vehicle was hit, it was sent to the center divider and first lane of the highway, where it came to rest blocking part of that lane. The truck came to rest in the center divider.

The girl, whose name was withheld pending the notification of her family, was one of Robertson's passengers.

Robertson and the girl both died at the scene.

Both Costa and Robertson's second passenger, a 10-year-old girl, were taken to Kern Medical Center by Hall Ambulance. Costa sustained moderate injuries; the girl sustained major injuries.