Work was shut down on a section of the Crosstown LRT tunnel on Wednesday after at least on worker was seen smoking marijuana, provincial transit agency Metrolinx says.

The workers were in the area of Eglinton Avenue East and Bayview Avenue when a supervisor became aware that at least one of them was smoking marijuana during breaks in work.

All work was suspended and as many as 25 workers were sent home for the day. Metrolinx COO says the workers were sent home because the site supervisor could not determine who was smoking marijuana.

An investigation is underway.

“Smoking weed on the job will not be tolerated and Crosslinx (our contractor) has assured Metrolinx that they are taking it very seriously. Workers will be fired if caught doing drugs or alcohol on the job,” spokesperson Anne Marie Aikins told CP24.

Metrolinx says Crosslinx has ordered its workers to take breaks on the jobsite. The contractor is also hiring extra security to patrol work areas.

The $5.3 billion light rail transit line is slated to be operational in 2021.