A semi-truck driver is dead today after the propane tanker he was driving rolled caught fire and exploded.The State Patrol says it happened around 7:20 this morning in Renville County on the western edge of Olivia, on Highway 71 near 212.Witnesses say the flames could be seen for miles and the explosion shook buildings in the area.Investigators are trying to determine the cause of the rollover.The drivers name hasn't been released.