The helicopter was helping in the search for a missing hunter when it went down. The cause of the crash was still unknown, and the victims' names hadn't been released on Sunday, but many were asking how this could have happened.

Trying to save one life, the three helicopter crew members lost theirs. Flags were at half staff at the company's headquaters on Sunday. The company operates 75 medical helicopter bases in 12 states.

Early Sunday morning, the helicopter crew from Muscle Shoals, Ala., was assisting in the search for a missing hunter. Good news came that the hunter had been found but, at nearly the same time, the bad news arrived about the crash.

"Everybody was focused on that and, the next thing we knew, the helicopter started going down," said Colbert County, Ala., Sheriff Ronnie May.

The National Transportation Safety Board and Federal Aviation Administration are investigating the deadly crash in the Alabama woods, while victims' families and the Air Evac family wait and wonder.

"It could have been a mechanical failure, could have been something as simple as a bird coming up out of a tree down below it that got in the tail rotor or main rotor system," says Jason Preston, a helicopter pilot with Ozark Mountain Helicopters in Branson.

Preston knows the risks of flying, and has even had a close call of his own.

"It was a dry belt failure, and I had to land in a field, unpowered," Preston said.

He says there are three possibilities when a helicopter goes down: mechanical failure, weather conditions, and pilot error. He says the Air Evac Lifeteam has a good reputation.

"I've met a few of their pilots, and I know they have some pretty strict standards. They do a lot of training," Preston said.

He believes the Air Evac crew had some disadvantages- total darkness at three in the morning, and only one engine.

"Most typically a double engine helicopter won't fly on one engine, but you can generally cruise enough to get you to a safe place to land," he said.

While many wonder what went wrong, folks in Alabama and Air Evac members everywhere are coping with the tragedy.

"We tried to do our jobs to the best of our ability but, when something happens like this happens, it really really hurts," said May.
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NBC Newschannel contributed to this report.