Discarded cigarette sparks grass fire near Carstairs, Alta.

Fire crews were called to put out a grass fire along the QE2 Highway on July 9, 2024, that authorities said was caused by a discarded cigarette. (Supplied)

A carelessly discarded cigarette nearly caused a major disaster along a major highway north of Calgary, police said Tuesday.

RCMP said the Carstairs Fire Department was called to a fire in the east ditch of the QE II Highway, between Township Road 298 and 294, at 2:10 p.m. on Tuesday.

The fire was contained quickly, officials said.

Police say the fire is believed to have been started by a cigarette tossed out of a car window, which is troubling given the current conditions.

"The Calgary area is under a heat warning. The ditches, and all other areas, are extremely dry right now," RCMP said in a news release.

"By throwing a cigarette out your window, you are risking property damage, and the lives of those around and the first responders who have to deal with the fires."

There is no fire restriction for Calgary or Carstairs, but according to Alberta Wildfire, a fire advisory is in place for the Calgary Forest Area, a large region of land in southwestern Alberta, stretching from areas west of Carstairs, Cochrane and Calgary, down to west of Pincher Creek.

Carstairs is located approximately 65 kilometres north of Calgary.