The unidentified woman, possibly in her 30s or 40s, was fatally injured about 9:15 a.m. EST at an automatic entrance to a blue line Metro subway train station, the Canadian Broadcasting Corp. reported.
"She got strangled ... [and] passed away on scene," Montreal police Constable Jean-Pierre Brabant said.
Investigators said a witness saw the woman's hair get caught in the escalator when she bent down to dislodge her scarf, the CBC said. The woman was in cardiac arrest when emergency personnel arrived.
The Fabre Metro station entrance was closed until further notice while authorities investigated the accident, the CBC said.