The fatal knife attack took place in Hamburg’s busy Jungfernstieg U-bahn station, the Hamburg Morgenpost (MOPO) and other German media report.
Police reported that the woman was badly injured during the incident and tweeted in the afternoon that she succumbed to her injuries. The child, who was a year old, died at the scene.
Die Mutter des Kindes und Exfrau des Tatverdächtigen ist den Verletzungen erlegen.
Die polizeilichen Maßnahmen am Tatort dauern an. https://t.co/hSD9HslweN
— Polizei Hamburg (@PolizeiHamburg) April 12, 2018
The 33-year-old suspect, who is from Niger, has since turned himself in and has been arrested.
“The crime was very, very terrible in its execution, very targeted and very, very extreme,” said police spokesman Timo Zill.
The motive for the crime is still unclear, states the MOPO.
Police believe a crime of passion was committed. A homicide team has since taken over the investigation.
The area around the Jungfernstieg underground station has been cordoned off over a wide area.
Some S-Bahn trains have been affected as a result of the incident and in the vicinity of the scene there are traffic obstructions due to road closures. Otherwise subways in the Hanseastic city are running normally.