At around 1900 this evening, Company 5 was dispatched to the 3600 block of Mt. Nittany Expressway for a tractor trailer roll over. Rescue 518 and Engine 514 responded on the run along with units from Company 3(Boalsburg). Rescue 518 arrived on scene to find one tractor trailer rolled over that had been traveling west bound and crossed the guard rail coming to a stop in the eastbound lanes. There were two injured patients who were able to assist each other in self extricating prior to fire department arrival. The crew from 518 assisted EMS while the crew from 514 and other arriving units were assigned to hazard control for a ruptured diesel tank and highway hazards. Units remained on scene for HazMat and wrecking crews to arrive and then went available a short time later.