SAN FRANCISCO (KGO) — BART police say they have arrested a suspect in the killing of a woman at Powell Street Station Monday night.

The 74-year-old woman was reportedly pushed by the suspect as a Millbrae-bound train approached, hitting her head on the train and falling on the platform. She was taken to the hospital and later died.

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The suspect has been identified as a 49-year-old transient man.

This is the first homicide on the BART system this year, police say.

BART PD arrested the suspect on the platform of Powell Street Station shortly after the incident, and he was booked into San Francisco County Jail on suspicion of murder and elder abuse, according to jail booking logs.

Investigators are still working to determine a motive in the killing.