A man was seriously injured when he ran a stop sign on his dirt bike and was hit by a car in Twentynine Palms Tuesday. About 4:15 p.m., the unidentified dirt bike rider was riding westbound on El Paseo Drive in Twentynine Palms. The rider ran the stop sign at Sunrise Road right in front of a sedan that was being driven northbound on Sunrise Road. The rider was thrown from his bike and suffered a possible broken leg. Morongo Basin Ambulance transported the dirt bike rider to Desert Hospital in Palm Springs. The driver of the car was treated at the scene and released.