A mother and son have been taken into police custody in connection with online threats about an explosive device, which prompted the evacuation of a West Island neighbourhood on Tuesday morning.

Police said no explosives were found following a significant police operation in Pierrefonds that included a search of a family home.

"It all started during the night when someone on social media had seen a video of someone that was looking like a threat," said Montreal police spokesman, Cmdr. Ian Lafrenière. "So we took that very seriously."

It is not clear yet whether the mother and son, who is in his 20s, will face charges, Lafrenière added. He also refused to comment on reports the family had ties to jihadists.

Around 200 people were asked to leave their homes on Tuesday morning as part of a "preventative" operation.

A security perimeter was erected around Gouin Boulevard West and Hortie Street. Witnesses say SWAT teams and an armoured vehicle were deployed to the area.

Quebec provincial police and the RCMP joined Montreal police on the scene.

Joyce Robertson was among those forced from her Pierrefonds home. (Sarah Leavitt/CBC)

"Police knocked on my door and said there is a problem in the area," said Joyce Robertson, who was among those forced their home.

"It was possibly someone with explosives."

Luis Amorim, another resident of the area, said police gave him 10 minutes to leave his home. He saw a woman — one of his neighbours on Laurin Street — being led away by police.

"[She was] not in handcuffs, but it looked like... she didn't want to leave," Amorim said.

Pierrefonds Mayor Jim Beis added little information about the nature of the threat, but sought to calm the concerns of residents.

Pierrefonds Mayor Jim Beis told reporters "everything is under control." (Ainslie Maclellan/CBC)

"It's important that... we stand together as a community and reassure the population that everything is under control," Beis told reporters.

The security cordon was lifted by Tuesday afternoon, allowing residents to return to their homes.

Sunnybrooke commuter train station was also reopened after being shut as part of the precautionary measures.