Metrolinx says an investigation is underway after a GO bus driver failed a drug and alcohol test while on duty this morning.

In a news release issued on Thursday, Metrolinx said a GO passenger reached out to Transit Safety and expressed concerns about an operator’s ability to drive.

The transit agency said that the driver had picked up customers in Brampton and was “immediately removed from service” at York Mills Station after the complaint was made.

The driver was tested for drugs and alcohol and failed the test, Metrolinx said.

About 15 customers were on board the bus at the time and no injuries or collisions were reported.

"Safety is our top priority at Metrolinx and we want to thank our customer for seeing something and saying something,” Metrolinx CEO Phil Verster said in the news release.

"Our drivers are extremely dedicated, responsible and trustworthy employees. This is a rare and very disappointing occurrence, which will be fully investigated. We want to assure our customers that every employee has a responsibility to safeguard the trust and safety of the public in attending work fit for duty—without fail.”

Metrolinx says the driver has been a GO bus operator for 30 years.