The Boulder County Coroner is working to identify a 17-year-old boy who died from a fall while climbing the First Flatiron.

The teen was free climbing alone Sunday just before 6 p.m. when he fell, according to the Boulder County Sheriff's Office. They said a Wilderness First Responder and another hiker who were in the area heard the boy hit the ground and tried to help him.

"They determined he had suffered massive injuries and called 911," Commander Mike Wagner with the Boulder County Sheriff's Office said.

The boy died before emergency responders were able to get to him.

Though nobody witnessed the fall, the teen posted a picture of his climb, showing his particular vantage point at the time shortly before he fell, Wagner said.

That photo will now be used in the investigation.

"It'll help again give us some information about date, time, location," Wagner said. "It'll help gauge where exactly he was on the Flatiron because it was an unwitnessed fall."

Though the exact height the boy climbed is unknown, Wagner said he fell more than a hundred feet.

Something investigators will try to answer is if this particular climb is something the teen had done or attempted before. They'll also try to further confirm he was alone when it happened.

The 17-year-old did not have any climbing gear or safety equipment with him, but was carrying camping gear and survival equipment, according to the Boulder County Sheriff's Office.

The investigation is being conducted jointly by the Boulder County Sheriff's Office and the Boulder County Coroner.