FORT WORTH — A 37-year-old woman was killed early Wednesday when she was hit by one vehicle and run over by another while walking on an Interstate 35W service road in far south Fort Worth, authorities reported.Police were looking for the driver of a “dark vehicle” that did not stop after running over the woman as she lay on the pavement, a police spokeswoman said.The Tarrant County medical examiner’s office identified the woman as Shanta Martin, 37. No town of residence was listed. Martin was pronounced dead at the scene at 4:55 a.m. Patrol officers responded to a 911 call shortly after 4:30 a.m. Wednesday from the 7100 block of the South Freeway on the northbound service road. A silver minivan that had left the interstate at the Alta Mesa/Felix Street exit was on the service road when it hit the woman, police Cpl. Tracey Knight said in an email. The minivan driver backed up to warn other vehicles and waited for police, Knight said. But another vehicle struck the woman and left without stopping, the driver told police.According to the medical examiner, Martin had massive blunt force trauma to her entire body because of “motor vehicle-pedestrian collision and secondary overrun.” Staff writers Domingo Ramirez Jr. and Monica Nagy contributed to this report.