Three people who jumped out of a GO Train Sunday night may have done so to try and help their sick friend who leapt from the train ahead of them.

It happened west of Danforth GO Station at around midnight.

Metrolinx said that it appears someone activated the emergency door on-board the train and jumped out while it was moving. Three other people then jumped out to help their friend after the train slowed.

Metrolinx originally said that the group had pried open the doors and then jumped out and that three of them were arrested. However the agency later said that none of them had been taken into custody.

One of the passengers – a man in his 20s – sustained serious, but non-life-threatening injuries, Toronto Paramedic Services said. He was loaded back onto the train and transported to Danforth Station where he was transferred to a trauma centre by paramedics.

Speaking with CP24 about the incident Monday morning, Metrolinx spokesperson Anne Marie Aikins called the incident dismaying and said the agency is “fully investigating” the circumstances.

“It is pretty bizarre. It’s unusual and incredibly dangerous,” Aikins said. “I don’t know how they did it or why they would do something like that.”

A witness told CP24 that the first man who jumped may have gotten sick prior to hitting the emergency door. Investigators and Metrolinx have not confirmed that detail.

Trains on the Lakeshore East GO Line were delayed for about an hour because of the incident. However morning service is not expected to be affected.