FLAGSTAFF, Ariz. (AP) -- A federal aviation spokesman says at least seven people are dead after two medical helicopters collided in mid-air in Arizona.

Ian Gregor of the Federal Aviation Administration says three others are in critical condition after the collision Sunday afternoon near a Flagstaff hospital.

He says all three people on one of the choppers were killed. Those victims include a patient and the pilot.

He wasn't sure whether the other casualties involved any people on the ground. He does not know what caused the collision.