«These train trips will make all stops to Milton. We apologize for the delays and thank everyone for their patience,» Metrolinx says.

Metrolinx says the disruption is due to a «safety incident,» while a group announced on Twitter that it is the result of a blockade.

Rising Tide Toronto, a grassroots collective, says a rail blockade is taking place behind the Lambton Arena, 4100 Dundas St. W, west of Jane Street.

The action is in support of the Wet’suwet’en hereditary chiefs and Tyendinaga Mohawks.

GO Transit, on its Service Updates webpage, warns of crowds at Union Station because of the incident.

«Given the way our trains operate through our network, this situation has the potential to disrupt customers throughout our entire system. Also, given the potential for system-wide delays, it is very likely Union Station will experience significant crowding during rush hour,» GO Transit says.

«Safety is our top priority and central to everything we do. We’re bringing in additional resources and are doing the absolute best we can given the situation. We know how inconvenient this is and we ask for everyone’s patience.»

Earlier on Tuesday, GO Train service was suspended on the Lakeshore East line from Union Station to Pickering. A safety incident near Guildwood station prompted that suspension, but GO Transit says on Twitter that the situation is now clear and Lakeshore East service has resumed with delays.

Metrolinx added that Lakeshore West is running with minimal delays between Union and Aldershot, with buses to Hamilton. All other lines are running with some delays, it added.