The TTC suspended subway service on a busy downtown stretch of Line 2 early Thursday due to oil spilled on the tracks.
No trains were running between St. George and Broadview stations, the transit agency said.
Riders will instead need to rely on shuttle buses or find an alternative mode of travel.
The TTC said at about 6:30 a.m. that crews were deployed to investigate the situation, but could not say when regular service might resume.
A spill of hydraulic fluid from a maintenance vehicle similarly closed the same stretch of Line 2 back in May, causing a morning of commuter chaos for thousands of customers. In that instance, it took several hours for the spill to be cleaned up.
At the time, TTC leadership said the agency was launching a review of the root causes behind the service outage, noting there had been seven such spills in 2024 alone.