Tim McKeown, 67, was en route to Talkeetna to help a person with a malfunctioning pacemaker when he passed out. Medics in the ambulance gave McKeown CPR but couldn't revive him.

"He's going to be missed a lot," said Carol Johnston, ambulance chief for District 5, which covers Houston and Willow. "He was a fixture at our department."

McKeown has been an active responder since 1998, said Clint Vardeman, deputy director of emergency services for the Mat-Su Borough. He worked with District 5 and District 4, which covers Talkeetna, Sunshine and Trapper Creek. McKeown's son, daughter and wife are all borough responders, Vardeman said.

McKeown's wife, Virgie Hartley, responded in the same ambulance to Friday's call, according to a borough press statement. McKeown was a medic to the end -- the patient was in the ambulance and McKeown was administering oxygen when he collapsed, according to the statement.

The ambulance crew put out a "medic down" call for help and started CPR. Trapper Creek, Willow and Houston medics responded. They worked on McKeown for 45 minutes without success, according to the statement.

Alaska State Troopers were called to the scene, at Mile 97 of the Parks Highway, at 2:41 a.m. after CPR started, according to a trooper press statement.

Neither Vardeman nor Johnston could say for sure Friday what caused McKeown's death. Both said it was possibly a heart attack.

Thursday was somewhat busy at the fire station, Johnston said, and she saw a lot of McKeown.

"He was in a good mood and bubbly all day," she said.

She said she could always rely on Mc- Keown to respond to calls or do community outreach activities with the department.

Vardeman said McKeown was a strong advocate of new technologies and techniques for the borough's medics. McKeown was the supply officer for District 5 and took the job seriously, making sure the ambulances were well stocked, Vardeman said.

Vardeman described the mood in the emergency services department as "somber."

"It's a pretty small group of people that we have, and I think everybody feels a loss whenever we lose somebody that's in our business," Vardeman said.

McKeown's family could not be reached for comment. Vardeman had no information Friday about funeral services.