The collision Sunday east of Flagstaff Medical Center was a few hundred yards away from a neighborhood that was spared the falling debris. Officials said they were unable to provide an account of what preceded the crash.
Lawrence Garduno, who lives about a half mile from the crash, said he heard a loud boom that rattled the windows. He drove toward the hospital and stopped to see the burning wreckage. "It kind of scares me," Garduno said. "If this had happened a half mile closer, it could have fallen on our house."
Witnesses said the weather was clear, and neither helicopter seemed to have
mechanical problems, CBS News reports.
An explosion on one of the aircraft after the crash injured two emergency workers who arrived with a ground ambulance company. They suffered minor burns and were spending the night at the hospital, but their injuries were not life-threatening. The crash, about 130 miles north of Phoenix, also sparked a 10-acre brush fire that was contained.
One of the helicopters was operated by Air Methods from Englewood, Colorado, and the other was from Classic Helicopters of Woods Cross, Utah. Both aircraft were Bell 407 models, said Ian Gregor, a spokesman with the Federal Aviation Administration.
Three people on the Air Methods aircraft, including the patient, died. On the Classic helicopter, the pilot, paramedic and patient all died. A flight nurse on the Classic helicopter suffered extensive injuries and was in critical condition at the hospital.
Matt Stein, a program director and lead pilot with Classic Helicopters subsidiary Classic Lifeguard Aeromedical Services in Page, Arizona, said his company's crew was landing at Flagstaff Medical Center carrying a patient with a medical emergency from the Grand Canyon's South Rim.
Stein didn't tell The Associated Press the names of the crash victims, except to say that the pilot for Classic was experienced with more than 10,000 hours of flight time. He added that it's rare for two medical helicopters to attempt to land at a hospital at the same time.
Flagstaff Medical Center doesn't have flight controllers, he said, and it's up to the pilots to watch each other as they approach.
Air Methods officials didn't return calls from The AP on Sunday night.
The helicopters spread debris across the scene. "They're not recognizable as helicopters," said Capt. Mark Johnson, a spokesman for the Flagstaff Fire Department.
The FAA is sending inspectors to investigate.
Hospital officials declined requests to interview the hospital president and the two burn victims.
It was the largest loss of life involving helicopters in Arizona since two news helicopters collided last summer while covering an auto chase near Phoenix, killing all four people on board.