A veteran Yellowknife firefighter is dead five days after being gravely injured on the job.

A city spokesperson confirmed Lt. Cyril Fyfe, 41, died Monday afternoon. He had been on life-support at Stanton Territorial Hospital ever since being trapped in a burning shed last Thursday.

Fyfe was inside the shed when the roof collapsed on him, pinning him and denying him oxygen. Another Yellowknife firefighter, rookie Kevin Olson, 24, died at the scene.

The city's fire chief, Mick Beauchamp, says friends and family members are struggling to cope with the incident.

"I've known Cyril since he was a little guy," Beauchamp says. "He was born and raised in Yellowknife and he's a wonderful father. Cyril is well respected in our department."

There was also praise for Fyfe from Calgary, from the parents of Olson. Olson's father, Brent, says he feels better knowing Fyfe was at his son's side when he died.

Firefighters were on the roof with axes and saws when it collapsed on Fyfe and Olson last Wednesday. No one else was injured.

It was Olson's second week on the job, while Fyfe has been a firefighter for 18 years.

There's still no word on what caused the fire. That's in the hands of the fire marshal, the Workers Compensation Board, the coroner and the police.

The RCMP say the investigation may take several days to weeks to complete.