High-rise condos make it more difficult for firefighters to respond to emergencies, according to Toronto's fire chief.

One of the biggest challenges for firefighters is getting crews to fires in high-rise condos, Fire Chief Bill Stewart said Wednesday.

"This city is going vertical -- anywhere we can build, we are building residential condos," he said.

Stewart said "vertical response time" will be an important issue to study in the days to come.

"By the time they get in, take control of the elevators, get their equipment, and make that first contact, that's six-and-a-half minutes," he said.

"That is significant."

Stewart originally became a firefighter in 1972, and said he followed in his family's footsteps.

"I'm a third-generation firefighter, my dad was a firefighter, and of course in our extended family my great uncles, and my son is a fourth-generation firefighter," he said.

He will retire on May 1 after almost 40 years of service.

"It's a new chapter in my life and we begin to move on."

With a report from CTV Toronto's Colin D'Mello