Mock terrorist attack puts Montreal's first responders to the test

The sound of gunshots and explosionsechoed in downtown Montreal today, but there was no threat to the public.

It was all part of an exercise to simulate a terrorist attack, and test how first responders would handle that kind of emergency.

The drillclosed down several downtown streets for much of the day.

More than350 people participated,includingparamedics,fire fighters and other emergency response workers.

Montreal policeCmdr.IanLafreniresaid the goal of theexercise was to see how responders "work together."

The exercise relied on volunteers to help act out several different scenarios, including a chemical attack on a city bus anda shooting atthe Black Watch Armoury.