July 10 (UPI) -- A 67-year-old man from Texas has died while hiking the Grand Canyon, according to park rangers who are warning of extreme heat. The hiker from Alvarado, Texas, was found unresponsive at about 11:50 a.m. local time Tuesday on Arizona's South Kaibab Trail, the National Park Services said Wednesday in a release . The cause of death was not released. Bystanders performed CPR while park medical personnel responded, but all attempts at resuscitation failed, it said. According to