The woman, identified only as being over age 70 from Truro, was taken by ambulance to Barnstable Municipal Airport, where she was flown to a medical facility, Wellfleet police wrote in a statement posted on the department’s Facebook page.
A female passenger in her car was taken by ambulance to Cape Cod Hospital with serious injuries.
The driver of the second vehicle, identified only as a woman over age 30 from Wellfleet, and her passenger, a girl about eight-years-old, were also taken to the hospital with serious injuries.
The crash involved two Toyota Rav4s traveling westbound on Route 6, toward Eastham, police said.
Police responded at about 11 a.m. to the crash near a Mobil gas station. Just before the crash, the vehicle driven by the elderly woman was reported to be driving erratically, the statement said.