A "trespasser incident" happened east of Appleby during the afternoon rush-hour commute, according to GO Transit.
Following the incident, GO Transit terminated westbound trains at Oakville. GO buses picked up passengers to Bronte and Appleby to connect with trains to Burlington and Aldershot.
The tracks at the scene of the incident reopened around 6 p.m., and the trains resumed all regular stops.
The incident caused major delays on the Lakeshore West line. The congestion at Union Station and on the tracks also delayed several trains on the Lakeshore East, Richmond Hill and Barrie lines.