Two medical helicopters collide in Arizona

Federal investigators are trying to determine what caused two medical helicopters to crash in mid-air Sunday afternoon, killing six people and critically injuring a seventh Sunday afternoon.

All three people on one of the helicopters were killed, including a patient and the pilot, said Ian Gregor, spokesman for the Federal Aviation Administration.

Three others aboard the second helicopter were killed and one critically wounded, Gregor said. The injured flight nurse remains in critical condition.

The helicopters were about 1/2 mile from Flagstaff Medical Center when they collided.

According to the FAA, both helicopters were Bell 407 models: one of them operated by Air Methods out of Englewood, Colo., and the other operated by Classic Helicopters of Woods Cross, Utah. Neither company returned calls from The Associated Press Sunday.

One of the choppers went down in an open field. The other crashed in a wooded area.

Nobody on the ground was hurt when the choppers went down, although three first responders were burned when a fuel tank exploded on the ground. Those people are expected to recover.

The fire from the crash and explosion touched off a 10- to 15-acre fire. Fire crews were able to get that under control relatively quickly.

FAA officials and the National Transportation Safety Board are on site to try and determine what happened.