There is no subway service on the western-most stretch of Line 2 Friday, and the TTC says the closure could last several days as crews work to repair communications cables damaged by a fire.
No trains are running between Kipling, Islington, Royal York, Old Mill and Jane stations, the transit agency says.
Shuttle buses are operating in their stead but significant delays are expected and riders are urged to use GO Transit from Kipling Station or the Lakeshore West line to get downtown.
Eastbound subway service from Jane Station is unaffected, the TTC said in a statement.
A fire broke out at track level at Islington Station shortly after 3:30 p.m. Thursday, according to TTC spokesperson Stuart Green.
The fire damaged a signalling box and a number of cables that enable communication between trains on the subway line. Crews are still working to determine how the blaze started.
Green said it will likely take several days for regular subway service to resume on that length of Line 2.
No one was injured in the blaze, Toronto Fire said.