Topton Fire Chief Randy Sicher said one of the teens fell down a 100-foot shaft early Saturday and was knocked unconscious. His three companions climbed down to him and became trapped.
The mine shaft is in an off-road wooded area in Berks County.
Police said the teens were pulled to safety after a seven-hour rescue involving at least 50 emergency workers from the area.
The boys were taken to a hospital for treatment of hypothermia, and for the head injury. Their names weren't released.
Police say the four teens were from Kutztown, and part of larger group camping near Bear Creek Mountain Resort.
Information from: Reading Eagle, http://www.readingeagle.com/