Call it a lesson that even though temps are lower than in the height of summer, it's still hot out.
Phoenix firefighters were called out to Piestewa Peak about 10:30 a.m. Sunday on reports of a 17-year-old girl who was weak and vomiting.
Rescue technicians hiked up to the girl's location and treated her on scene with IVs and medication. She was able to walk down with assistance.
While on the mountain, firefighters treated two other teenage patients. They also had to rehydrate and needed help coming down the mountain.
Luckily, no one needed to go to the hospital.
"Fortunately we didn't have to carry her down or fly her off the mountain. If we can stabilize you on the mountain with some IV therapy and maybe some blood sugar, some thiamin or something, so we can get you down the mountain, that's the best way for everyone involved," said Phoenix Fire Captain Tony Mure.
"Probably took on a little more than she could for her exercise level. They were several people out there overheating... know your fitness level. This is not entry level training."
Firefighters say the teens were dressed properly and had water and a cell phone -- but the heat just became too much to handle.