The Kitchener Fire Department says smoking was the cause of the fire that left one man dead in an apartment building Wednesday morning near Grand River Hospital.

At 7:09 a.m., firefighters got a call about a fire in a unit on the third floor of an apartment building at 812 King St. West, according to interim deputy fire chief Rob Martin.

Around 20 firefighters went to the scene, where crews evacuated the third floor and several other floors due to heavy smoke and other toxins from the fire, said Martin.

(Melanie Ferrier/CBC) Crews also pulled out a service dog from the unit where the man died. Martin said the dog was found unconscious, brought out of the building with the assistance of paramedics and revived at the scene. The dog is now in the care of the Humane Society.

Kitchener Fire officials say the fire was caused by the 61-year-old man who was smoking in his apartment, and was using oxygen.

The man was the only person in the apartment, which he shared with his service dog.

"The [man] had some mobility issues," said Chief Fire Prevention Officer Tom Ruggle. "He had had a spinal cord injury a number of years ago and only had the use of one hand."

Ruggle told CBC News that the Kitchener Fire Department is not releasing the man's name yet because they haven't received confirmation from Waterloo Region police that the man's next of kin have been notified.

Smoking a leading cause of fire deaths

This is the fourth death in the last three years in Kitchener caused by smoking, said Ruggle.

"Smoking is still one of the leading causes of residential fires," he said.

Some residents have been able to return to the apartments but firefighters are still working to clear the third floor.

The fire marshal's office has been notified of the fire, he said.