The City of Longueuil issued an update on its website around 4:30 a.m. Friday to let residents know the lockdown was no longer in effect.

People in a part of Longueuil, Que., were being asked to stay indoors with their doors and windows closed on Thursday after a train derailed in the morning, spilling an unknown quantity of hydrogen peroxide.

Water vapour pouring off the derailed CN train in Longueuil -- police have asked those in the area to stay inside, saying they don't know whether the fumes are safe. The fire department is on the scene, dousing the train as a precautionary measure. @mtlgazette pic.twitter.com/2hiId0liEV

Emergency services are at the scene of a train derailment Thursday morning on Montreal's south shore, where they are urging citizens to stay away from the area.

Eight cars of a Canadian National train derailed today (Thursday, Nov. 14) in suburban Montreal, releasing a cloud of a potentially hazardous material and leading to a shelter-in-place order for nearby residents as well as area schools.

People in a part of Longueuil, Que. were being asked to stay indoors with their doors and windows closed on Thursday morning after a train derailed in a train yard, spilling an unknown quantity of hydrogen peroxide.

The City of Longueuil, Que., said the chemical was hydrogen peroxide. It’s also advising people living within 800 metres of the derailment to stay inside.