Many GO Transit commuters in the Toronto area were warned to expect delays Wednesday after a downpour washed out a section of track on the Lakeshore West line.

Torrential rain caused flooding that destroyed a stretch of rails between Mimico and Port Credit, about 10 kilometres west of the downtown area, just after 6 p.m. Tuesday.

Crews were on the scene early Wednesday trying to repair the track as fast they could, but the commuter train agency was warning that all morning commutes on the line would take 10 to 15 minutes longer than usual.

On Tuesday night, the Lakeshore West line washout delayed the ride home for several thousand passengers as trains were cancelled and shuttle buses were deployed.

Natasha Heck was one of many riders headed to Port Credit when the problem became apparent.

"I hopped on the 603 train and the next thing you know we're stopped at Bathurst. Then we continue along to Exhibition and sat there for 30 minutes," she said.

"Lo and behold, the next thing you know, the tracks are flooded and we can't continue westbound. So we were told to continue back to Union [Station] and now we're all waiting."

At one point, hundreds of passengers were jammed on the GO bus platform across Bay Street from Union Station, Toronto's main transportation hub.

Then just before 8 p.m., GO Transit announced a change in plans. Passengers were directed to board trains going westbound to Mimico, where they would connect with a shuttle bus to Port Credit. Anyone proceeding past Port Credit was then put on another train.

Ripple effects from the flooding and train diversions also meant some evening trains on the Lakeshore East line had to be cancelled