Montreal transit officials say metro service should be back on regular schedule Thursday morning, after a fire shut down the green line overnight.

The fire broke out in a subway access well at Rouen and Frontenac Streets in the east end just before 7 p.m. Wednesday.

Communication channels along the green line were cut off because the fire damaged telephone and ventilation cables, public transit officials said.

The green line was shut down completely as a safety precaution and buses shuttled passengers along the route.

Service resumed between the Angrignon and Frontenac stations late Wednesday night but several stops were closed until Thursday morning.

It's not clear what started the fire, but the Montreal Transit Commission said it was investigating.

With files from the Canadian Press