MONTREAL - The STM reported on Friday evening that the Metro's Green, Orange and Yellow lines were disrupted due to an intervention by emergency services, but service was gradually returning as of 9 p.m. Friday.

The lines initially shut down around 8:15 p.m. Montreal police said someone sprayed pepper-spray inside Berri-UQAM station. No suspects were arrested. The station was evacuated and the irritant affected two people, police said.

An STM representative told CTV News that "certain stations" on the Orange and Green line had been evacuated for "emergency ventilation."

The spokesperson said the Yellow line was completely shut down, the Orange line was snarled between Georges-Vanier and Sauve stations and the Green line was closed between PIE-IX and Atwater stations.

The STM initially expected service to resume at 9:30 p.m. but at 9 p.m., the agency tweeted that service was slowly returning. They warned, however, that increased ridership due to backlogs were expected and some trains could still be delayed. 

The agency said transit users could use their website to check for updates

This was not the first time pepper-spray has snarled Montreal Metro lines. In January, pepper-spray used in the metro caused a major shutdown during rush-hour.