Police are looking into whether the man was deliberately pushed in front of the train at the Kottbusser Tor U-Bahn station in the popular Berlin district.
According to police, two groups had clashed with each other around midnight on Tuesday. Then, one man pushed another man in front of an arriving train.
He was so badly injured that he died shortly after the incident.
The police questioned witnesses and viewed video recordings of the scene, reported the Berliner Morgenpost.
A homicide squad has taken over the investigation, stated Berlin's police department on Twitter.
Bei einer Auseinandersetzung zwischen mehreren Personen wurde heute Nacht ein Mann im U-Bhf. #KottbusserTor vor einen einfahrenden Zug gestoßen und kam ums Leben. Die 4. Mordkommission unseres #LKA hat die Ermittungen aufgenommen.
— Polizei Berlin (@polizeiberlin) October 30, 2019
The suspect fled the scene immediately following the incident.
Police are currently evaluating CCTV footage for additional information on the identity of the victim and the other people involved.
Following the incident, U-Bahn traffic was temporarily interrupted and there were significant delays on the U8 line. The driver of the train who hit the man was looked after by pastors.
In 2018, Kottbuser Tor was deemed to be Berlin's second most dangerous U-Bahn station, based on 119 injuries recorded there in 2017.
The shocking crime follows a spate of similar incidents which have sparked a national debate about security at railway stations in Germany.
In July this year, an eight-year-old boy was killed when he was pushed under a high-speed train at Frankfurt's main station by a man.
His mother was also pushed onto the tracks but was able to save herself.
In July, a woman was pushed in front of a train at the station in the small town of Voerde, near Duisburg, in North Rhine-Westphalia. The 34-year-old mother-of-one died at the scene.
Earlier this year, a 41-year-old woman pulled an unknown 17-year-old by her hair onto train tracks at the U-Bahn at Berlin’s central Alexanderplatz station. The teenager managed to save herself before a train arrived.
In 2016, a 20-year-old woman also died after she was pushed in front of U-Bahn tracks in Berlin by a mentally ill man.