The first rescued horse was tranquilized, but it took five minutes of the horse being airborne before crews rested the animal in a safe landing spot.
"You have to do a little bit different than you would with, say, an inanimate object because you have something down there that's alive," said Karim Slate, who piloted the rescue helicopter. "So we watch it pretty closely and don't fly it too fast, make sure that the animal looks fairly comfortable.
Slate says he flew about 50 mph. There were tense moments, but the landing was a success.
With one horse out of the scene, firefighter Scott Lake and his crew went back for the second horse.
"He'd been there for six hours and so the time, the exhaustion level on the horse was starting to get to him. So we were doing everything we could to hold him up and just wait for the helicopter to come in and get the horse out," he said.
The two airlifted horses were on a four-day trail ride through the Cleveland National Forest. The U.S. Forest Service says it is unclear how four horses and their riders ended up in the ravine Friday morning.
One horse died during the ordeal, and the fourth horse was able to walk out from its location once a path was cleared.
For the rescuers, handling horses is part of the job, but there is uncertainty when dealing with large animals.
"Normally when you have a patient, you can talk to them, you can interact so you can comfort them verbally. With a horse, you're petting them, and you've got to really make sure that you're in the areas that they're comfortable with you being there," said Lake.
The operation was time consuming and executed with care. Once the horses were out of danger, the riders were hoisted from the ground. They were not injured.
The three horses that were rescued appeared to be OK.
Fire crews landed in Fullerton following the rescue.