Officials say 19-year-old Nicholas Cendoya was located just before sundown by a hiker who was unrelated to the search. The hiker told a fire crew, who was also in the area on an unrelated training mission, where to find Cendoya. A helicopter arrived to remove Cendoya from thick brush.
Cendoya was rushed to Mission Hospital in Mission Viejo, where he was listed in serious condition.
"He is weak, severely dehydrated and slightly confused," said Div. Chief Kris Concepcion of the Orange County Fire Authorities. "It was described that when the rescuer was lowered, he was lowered about 10 feet from Nick and he had actually lost sight of Nick. That's how thick the brush was."
The focus now shifts to Cendoya's missing companion, 18-year-old Kyndall Jack. Officials did not say if Cendoya was able to provide information on her whereabouts. They continued the search for her into the night.
"We will be asking Nick [if] he can give us information, then we'll hopefully use that in the search for Kyndall," Concepcion said.
Earlier in the day, hundreds of the missing teens' friends gathered for another day of searching Holy Jim Canyon.
"It's scary really because I know we've walked around a lot of different areas today, and we have no idea where they could be," said Heather Flores, a friend.
Authorities said they sent a helicopter as well as ground crews to check rugged terrain where volunteers thought they saw flickering lights Tuesday night and Wednesday morning -- both within a mile of the Costa Mesa teenagers' car.
The sighting provided hope for their families, who have gone with little, if any sleep, for the past three days.
Jack and Cendoya called 911 for help around 8:30 p.m. Sunday. They told dispatchers they were hiking on a trail but couldn't find their way back down the rugged terrain. They also said they ran out of water. Their cellphone batteries died before police could trace a signal.
On Wednesday afternoon, a couple of volunteers were yelling out the names of the missing hikers, and a man and woman responded.
"We heard a girl's voice yell help. It was mostly a guy's voice yelling though, but it was in a completely separate canyon. It wasn't anywhere close to us," said friend Jenny Hueber.
Hueber and her friend guided authorities in a helicopter to the spot where they heard the voices. They returned saying they saw two people, but there was no confirmation that the people they spotted were their friends.
Crews from several agencies searched a two-mile radius from where Jack's car was parked.
"We're going to increase the number of our ground searches. We're going to commence with air operations in strategic areas that have high terrain that are difficult to traverse," said Capt. Jon Muir with the OCFA. "It's going to be a combined effort. We're not going to stop until we have a good resolution."
One close friend of the two teens, Summer Rudis, said Kyndall Jack opened a message on her phone that Rudis had sent her early Monday morning through Snap Chat. Rudis also said she was supposed to go on the hike with the missing teens, but she decided to spend time with family.
"I work with Nick at Ruby's Diner, and I just love both of them a lot," Rudis said.
Friends of Kyndall Jack say she smoked cigarettes and always carried a lighter with her. They also said she wasn't an avid hiker.
Jack's car was towed away late Tuesday. Authorities believed one of the hikers may have been hurt, making it harder to find them. They were optimistic because the weather conditions have not been bad in the last few days, with temperatures dropping to the 50s at night. The teens were also said to be physically fit, which improved their chances for survival.