As the sprinkler system activated and water rained down in the fast-food restaurant, the man entered an adjacent pharmacy and took another woman hostage, whom he also threatened to burn in the ensuing drama, said police.
"Eye-witnesses reported hearing shots, others spoke of smoke bombs, but we can not confirm any of that so far", a police spokesman told news channel NTV.
The woman was released and was taken to hospital.
The perpetrator then holed up in a pharmacy behind the station, taking a woman hostage.
The suspect was severely injured when police stormed the pharmacy and later received CPR.
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A man who held a woman hostage at Cologne's main train station also injured two other people Monday, and police said his motives weren't clear but they were investigating if he had extremist connections or beliefs. "The investigation is considering all possibilities and we are not ruling out terrorism", said Cologne deputy police chief Miriam Brauns. During their search, they discovered the identity documents for a 55-year-old Syrian migrant with a German residence visa valid until 2021.
Police tweeted that the hostage was slightly injured and was now being treated. Police commandos were deployed and the busy railway station was closed off to all passengers and trains. "We have made contact with the attacker", he said, adding that police were trying to clarify "what does this man want, what are his demands, and is he armed?" "A female hostage has sustained light injuries and is being tended to".
German railroad operator Deutsche Bahn tweeted that some of the station's tracks were shut down temporarily.
Police later said the suspect, who was badly wounded when police arrived, claimed to be a member of the Islamic State (IS).
Police spokesman Christoph Schulte said that officers have stormed the pharmacy where the man was holding a woman and that he was suffering from unspecified injuries.