One person was seriously injured Monday in a single-car accident on Highway 154. According to County Fire officials, emergency crews responded at 1:38 p.m. to a silver Mercedes along the side of the highway at East Camino Cielo Road. The responders found a bystander performing CPR on the car’s driver, who was rushed to the hospital in an ambulance. Highway 154 traffic slowed in the location but lanes remained open. The driver’s condition is unknown, and the cause of the accident remains under investigation, officials said.