Metrolinx and Toronto Paramedic Services are staging their largest joint emergency simulation this Saturday night at Union Station.

Be warned, says Metrolinx. The exercise will feature 150 actors and make-up artists with staged smoke at the platform level.

This drill - "the largest joint emergency exercise to take place at the busiest transit hub in the country"- happens  late evening on Saturday, Nov. 2. It will end early morning on Sunday, Nov. 3.

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Metrolinx says people in the area may witness volunteers pretending to be seriously injured, lots of emergency vehicles and first responders acting out the response protocol.

Metrolinx is promising no impact to transit service (whew!) but there will be some some road/sidewalk diversions.

Fortunately, the Toronto Maple Leafs are playing in Philadelphia (look out for Gritty!) and the Raptors are in Milwaukee to face the Buck in a playoff rematch. Fleetwood Mac plays Scotiabank Arena the night before.

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"Safety is critical to everything we do at Metrolinx, and it is important to regularly test our emergency preparedness to ensure our staff and first-responders are ready in the event of any type of critical incident at Union Station," said a statement from George Bell, Metrolinx VP of Safety and Security.

Do not call 911, urges Metrolinx. And though it all seems  like an Instagrammer’s dream, Metrolinx is urging onlookers to please not get in the way. And if you’re squeamish, well, best stay away. You’ve been warned.