The incident happened around 9:15 a.m. ET Thursday at an unsupervised, automatic entrance to the Metro station on the blue line.
"She got strangled… and the woman, aged around 30, passed away on scene,” said Const. Jean-Pierre Brabant of the Montreal police.
A witness told investigators that the woman's hair also caught in the escalator after she bent down in an attempt to dislodge her scarf.
The woman was in cardiac arrest when firefighters and paramedics arrived on the scene.
UrgencesSanté said the woman appeared to be in her 30s, but could have also been in her 40s.
The Fabre Metro station is in the Montreal borough of Villeray-St-Michel-Parc-Extension.