The deadly crash happened Saturday around 10:20 p.m. on Camp Rock Road, north of Rabbit Springs Road.
The victims killed were identified by the coroner's office as Willow Sanchez, 11, Daytona Bronas, 12, and Sandra Mizer, 13, all Lucerne Valley residents.
CHP says the four pedestrians - two of them in wheelchairs - were on Camp Rock Road when they were hit from behind by a pickup truck described as a white 2002 Chevrolet Silverado, which was traveling northbound.
After the crash, the driver and a passenger fled the scene on foot.
The San Bernardino County Fire Department pronounced three of the girls dead at the scene. The fourth victim suffered major injuries and was airlifted to Loma Linda University Medical Center.
Lucerne Valley Unified School District Superintendent Peter Livingston identified the surviving victim as Natalie Coe.
CHP says it's unclear whether drugs or alcohol was a factor in the crash.
Authorities ask anyone with information regarding the crash to contact CHP Officer L. McAllister of the Victorville CHP office at (760) 241-1186.
A small memorial honoring the victims was set up at the crash scene. A GoFundMe page has also been established to help the girls' families with burial costs and to support the surviving victim, who remains at a hospital fighting for her life.