Smoking materials being “improperly” discarded at a townhouse in the Humber Bay Shores neighbourhood was the cause of a four-alarm blaze last week, Toronto fire said.

Three district fire chiefs and 13 firetrucks responded to multiple calls for a fire in the area of Lake Shore Boulevard and Palace Pier Court at around 6 p.m.

The fire broke out on the balcony on the third floor of one of the residences. The flames then spread to the roof of the building and to an adjourning unit north of the balcony.

The blaze was initially ruled as a five-alarm fire but firefighters now say it did not surpass a fourth alarm.

While responding to the blaze, Toronto Fire said one of the three district chiefs suffered critical injuries as a result of a medical event. He was taken to hospital where he was later listed in stable condition.

No other injuries were reported in the incident.

Following an investigation conducted by the Office of the Fire Marshal and Emergency Management, officials said the cause of the blaze was deemed “accidental.”

“The investigation has concluded the cause of the fire was accidental, involving improperly discarded smoking articles on the third-floor deck.”

Toronto Fire said they are reminding people to smoke outside and use soak lit materials in water prior to disposing them.