CNN
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Seventeen people were injured – four of whom remain in critical condition – in a knife attack at Hamburg’s Central Station, the city’s fire department told CNN Friday evening.

German police said they have arrested a 39-year-old German woman, who they believe acted alone, after a major police operation.

Six people were “badly injured,” while seven others were “lightly injured,” the fire department said. Dozens of emergency services were active on the scene.

Police previously said that several people had sustained “life-threatening injuries” in the attack, but reliable figures on the number of injured people were not immediately available.

Investigations into the incident are ongoing. Police told CNN that officers are not currently assuming any political motivation, but were looking into whether the suspect had been in a state of mental distress.

Video footage from the scene filmed by CNN’s affiliate RTL Germany shows people in forensic suits inspecting the area while police gather in the train station.

Following the attack, Germany’s Friedrich Merz thanked the city’s emergency responders for their assistance and said that his “thoughts are with the victims and their families,” according to federal government spokesperson Stefan Kornelius.

Hamburg’s Central Station is the busiest passenger railway station in Germany, with more than 550,000 travelers per day, according to the city’s website.

Germany has faced rising rates of knife crime in recent years, with some incidents stirring up tensions over migration ahead of parliamentary elections in February.

Some in the country were concerned by a series of high-profile attacks allegedly carried out by asylum seekers or migrants.

In January, a 28-year-old man from Afghanistan was arrested following a knife attack in the German city of Aschaffenburg in which two people were killed, including a toddler.

Last year, a Syrian man turned himself in and confessed to stabbing to death three people and wounding several others at a festival in the western German city of Solingen.

This is a developing story and will be updated.