GO Transit says service has returned to normal on the Barrie line after a person was fatally struck by a GO train south of its Newmarket station on Tuesday evening.

The transit agency had warned of delays, but at about 9:45 p.m., it said service on the Barrie line has been restored.

Metrolinx spokesperson Matt Llewellyn said the person was struck on the Barrie line shortly before 5 p.m. York Regional Police and GO Transit officials investigated the death.

York Regional Transit (YRT) added five buses to its routes to transport stranded passengers from Aurora GO to Newmarket GO to East Gwillimbury GO.

Llewellyn said a GO train had stopped south of the Newmarket station and another train had stopped at the Aurora station during the disruption. Service to Barrie was temporarily suspended at Union Station.

Passengers were urged to be patient, told to take alternate routes if possible, and were allowed to use their GO tickets or Presto cards on the TTC at staffed entrances at Downsview and York University.

Anne Marie Aikins, another spokesperson for Metrolinx, expressed condolences to the family of the person killed.

"Thoughts are with their loved ones and our crew, customers and the first responders," she said.

Update: Barrie <a href="https://twitter.com/hashtag/GOtrain?src=hash&ref_src=twsrc%5Etfw">#GOtrain</a>: The delays we were experiencing as a result of a fatality south of Newmarket have ended and service has returned to normal. Thank you for your understanding this evening. —@GOtransitBR