A 16-year-old girl is not expected to survive after she suffered life-threatening injuries when she was struck by a vehicle near a busy intersection just west of San Marcos High School Thursday morning, authorities said. The collision happened just after 6:30 a.m. on South Rancho Santa Fe Road south of San Marcos Boulevard, the sheriff’s office said. People called 911 and told dispatchers that a teenager had been struck and remained down in the roadway, the agency said in a news release. San Marcos firefighters immediately rendered medical aid to the girl, then took her to a hospital with “major, potentially life-threatening injuries,” the office said. The teen was a student at the nearby high school, which San Marcos Unified School District Superintendent Andy Johnsen confirmed in a message to students and families, noting he was “heartbroken.” “Unfortunately, the student was struck by a car and sustained serious injuries, and their family has granted permission to share that she is not expected to survive,” Johnsen wrote. “I can personally share that this news is so sudden and saddening, it will no doubt have an impact on us all,” he said, adding that the school intended to have crisis and counseling teams on hand for the campus community. The sheriff’s office said the initial investigation indicates the driver was headed north on South Rancho Santa Fe Road, headed toward the intersection with San Marcos Boulevard when the teen crossed the road. The driver stayed at the crash scene and is cooperating with investigators. Neither drugs nor alcohol are believed to have been a factor in the collision, authorities said. Investigators are asking anyone who witnessed the collision or caught it on a dash cam to contact sheriff’s Deputy James Clone at 760-510-5047 or via email at [email protected].