At 14:18hrs Truck 21 was sent to the 1000 block of Texas Parkway for the reported MVA. While enroute additional information was received advising of 3-5 vehicles involved with multiple people trapped adding Engine 22, Battalion 21 and 2-additional Medic Units. Upon arrival a 3-car MVA was found where one car had jumped the center median, became airborne, and then struck 2-vehicles in the oncoming lanes, 1-head on. Scene size-up revealed a total of 3-patients with 2-suffering open lower extremity fractures and 1-driver trapped. With Truck 21 undertaking extrication Engine 22 arrived and assisted with patient care and hazards while Engine 33 was requested for LZ responsibilities. Following completion of extrication, packaging and loading of patients, safe departure of the aircraft and securing hazards all units returned to service.