A man who police believed had barricaded himself inside an apartment on the Plateau late last night brought a part of the Main to a standstill this morning, but it turned out to be a false alarm. 

The operation closed Saint-Laurent boulevard between Sherbrooke and Roy for about 10 hours.

It was around 9:30 a.m. when police finally lifted their wide perimeter after officers entered the apartment building on St-Laurent  near Pine avenue and emerged emty-handed.

"The SWAT team officers went inside two apartments in the building looking for the suspect and any weapon, nothing was found," says police spokesperson Daniel Lacoursiere. 

The suspect is a man in his 30's who police say was arguing and making threats towards neighbors. He was also wielding a handgun.

It is not clear if the man was a resident of the apartment or just visiting.

Police say they're still looking for him and the investigation continues.