A corroded cable caused the power to shut down on Line 2 on Thursday morning that led to a chaotic commute for many.

There was no subway service between Pape and St. George stations for several hours leaving many commuters angry and frustrated.

The TTC said in a news release that the problem began when a corroded cable came into contact with a fence at track level on the Bloor Viaduct.

It resulted to shorting out of electrical power on Line 2, the transit agency said. The circuit breaker system cut power to prevent serious damage to their system or the the bridge structure.

"Staff are taking corrective action to protect against any further incidents of this nature," the TTC said.

"This particular part of Line 2 is 53 years old and is already the subject of a thorough review of the entire line's infrastructure - everything from power supply to tunnel liners to rail and drainage - to identify medium and long term capital investment needs."

The agency said the full assessment will be presented to the board next year.