An Indiana man died while hiking on the trails near Horsetooth Rock early this afternoon, a Larimer County coroner said.

Tommy Ray Harrison, 52, was visiting his daughter from Sullivan, Ind. The two were hiking the trail between Soderberg and Horsethooth Rock trails around noon when he suffered what appears to be a heart attack, said Greg Fairman, deputy coroner.

"He was flying out tomorrow," Fairman said.

Harrison's daughter told authorities the two started hiking around 11 a.m and had been on the trail for an hour and a half when Harrison began having back pains that moved to his chest. After telling his daughter he wasn't feeling well, she suggested they start walking back down the trail. As she called 911 from her cell phone, she heard her father fall to the ground, Fairman said she told authorities.

"She did CPR for almost three-quarters of an hour and rescue workers worked on him for almost an hour" once they arrived, Fairman said. A North Colorado Med Evac helicopter was called and carried his body to a clearing west of the main trailhead, where Fairman officially pronounced him dead.

The coroner's office will perform an autopsy on the body today, Fairman said.

Harrison seemed to be in relatively good health, Fairman said. His daughter said he didn't have any pre-existing heart conditions and that he had just passed a series of cardiac workups performed by his doctor, Fairman said.

The altitude could have contributed to his death, Fairman said, because Harrison wasn't used to performing strenuous activity at this elevation.

"We see this with people who come out from sea level elevations," Fairman said. "They go from zero to 4,000 feet. It can be very hard on the body."

Fairman said Harrison and his daughter were hiking at 6,600 feet when his chest pains started.