(Courtesy of Phoenix Fire Department)

Engineer Paramedic Gary Johnstone

An off-duty Phoenix firefighter has died and a teenage boy is in critical condition after a rappelling accident on Camelback Mountain.

The firefighter was identified by the department as Engineer Paramedic Gary Johnstone, 50. He was a father of three who had been on the force for nearly 15 years.

Johnstone was rappelling off a formation called Sugar Cube when he and two 15-year-old boys fell. A third boy, Johnstone’s son, was not hurt.

Police are investigating the accident, which closed the Echo Canyon side of Camelback Mountain on Friday, but no foul play is suspected.

Phoenix Fire Department spokeswoman Shelly Jamison says Johnstone was one of the members of technical rescue team. It responds to the same type of accidents as the one that took Johnstone’s life.

"They embrace this. They love climbing, they love outdoor activities, so for Gary to have been engaged in this type of activity on his day off probably isn’t that unusual. It’s what they love to do," Jamison said.

In a press conference Phoenix Mayor Greg Stanton said the City of Phoenix and the Phoenix Fire Department were grieving Johnstone’s loss.

"And we are all reminded of how painful it is when the community looses the kind of person who will walk into a fire to protect us, and serve any one of us at the time in our lives when we need the help most," Stanton said.

Jamison said Johnstone was a well-loved member of the department who played bagpipes in the honor guard. Johnstone had spent nearly 25 years in firefighting, including 15 in Phoenix.

Updated 8/8/2014 at 4:47 p.m.