Toronto police say a 57-year-old man faces a first-degree murder charge in the death of a man who was apparently pushed in front of a train at one of the city's busiest subway stations Monday morning.

Det. Rob North told a news conference Monday night that police are looking for witnesses to the incident. He also appealed for anyone who may know the victim, who has yet to be identified, to come forward.

North says the deceased is described as Asian, in his 50s or early 60s, with white hair, adding that he had no connection to the accused.

North says the suspect did not flee and was arrested in the area about 20 minutes after the incident.

He says investigators have reviewed surveillance video from the Yonge-Bloor subway station, which connects the city's two primary transit lines.

He says it shows the two men on the platform as an eastbound train is entering the station. They then have an "interaction," and one of them is pushed and falls under the train.

"The push happened very quickly, and there was none to very limited interaction between our deceased and our accused," North said, adding that the video is very clear.

North did not give reasons, but said investigators believe first-degree murder was the "most appropriate" charge.

Toronto Transit Commission spokesman Brad Ross said intentional deaths on the subway system are extremely rare, adding the last case took place in 1997 when someone was deliberately pushed onto the tracks.

The TTC will work to ensure the driver of the train receives any help that may be necessary, he said.

Ross said the Yonge portion of the station, which serves as the centre point of the city's east-west transit line, will remain closed while police continue their investigation.