A man died Monday after being found unresponsive at the Boulder Rock Club, but investigators and club officials say it's unclear what happened.

At about 2 p.m. Monday, employees and other climbers at the Boulder Rock Club, 2829 Mapleton Ave., heard what they thought was a person falling and found a man who appeared to be in his mid-60s unresponsive on the floor, according to John Bicknell, a co-owner of the climbing gym.

Staff members began performing CPR until paramedics arrived, and the man was transported to Boulder Community Hospital, where he was pronounced dead, according to police.

The man's identity has not yet been released by the Boulder County coroner, pending notification of his family.

"Everybody at the Boulder Rock Club is saddened and shocked by this," Bicknell said, adding that grief counselors were at the club Tuesday. "Not only shocked, but puzzled. We don't know what happened."

Bicknell said the climbing gym was not busy at the time of the incident, so nobody witnessed what happened before the man was found.

He said employees heard a sound "consistent" with a fall, but they didn't see injuries on the body that indicated the man fell far.

"Nobody actually saw anything, so anything is just speculation," Bicknell said. "We don't know if he fell or if there was a medical issue."

In the area where the man was found, he could have been on the bouldering wall or bouldering on the climbing wall, which is allowed up to 14 feet, Bicknell said.

He said the man was wearing a harness, a chalk bag and climbing shoes, but obviously had not been using one of the club's auto-belay devices prior to being found.

The man did not have a monthly membership to the club, instead using a punch card on each visit, Bicknell said.

Boulder police spokeswoman Kim Kobel said investigators at this time do not believe anything criminal occurred.

The coroner's office will conduct an autopsy and investigation to determine the official cause and manner of death.

Camera Staff Writer Joe Rubino contributed to this report. Contact Camera Staff Writer Mitchell Byars at 303-473-1329, byarsm@dailycamera.com or twitter.com/mitchellbyars.