Four men required treatment after their silver Honda Accord was involved in a one-vehicle collision on the main Omagh to Newtownstewart Road on Sunday.
Three have been discharged from hospital but one is still receiving care.
Police have appealed for information about the crash.
It was reported at around 1pm close to the Mellon Country Inn between the Gortnagarn Road turnoff and the Beltany Road into Newtownstewart.
Officers believe another car may have been at or near the scene at the time of the collision and have asked the driver of this vehicle to contact them.
Information can be passed on to the PSNI on 0845 600 8000.