Police are investigating a case of what appears to be deliberate vandalism at the Royal York subway station.
It had caused a closure of the stop on Line 2, but the station has since reopened.
TTC officials say the vandalism happened at about 5:30 a.m., before the subway was running.
They are not giving any details on what equipment was damaged, other than to say it was on track level.
A failsafe mechanism was in place that allowed the subway to continue running through the morning rush.
They had to close the station mid-morning, though, to allow officers onto track level to conduct their investigation.
There is no information at this point on a suspect or suspects. Police say the person responsible could face a charge of mischief.