According to the police, an event took place in the evening in the three-storey building of the Jehovah's Witnesses. According to the Hamburg interior authorities, the shots were fired around 9 p.m. Police forces were nearby, were at the scene of the crime a few minutes later and then "penetrated the object very quickly". The officials were still on site on Friday night with a large contingent and called for "no rumors to be spread".

According to the information, the officials found several dead and seriously injured in the building. They also heard a shot "from the upper part of the object" and found a person there, a police spokesman said. There is no evidence of the perpetrators fleeing. Rather, there are "indications that a perpetrator might be in the object, might even be among the dead." The person found upstairs in the building is "possibly" the perpetrator or one of the perpetrators, the police spokesman explained.

The Hamburg interior authority published a warning at the beginning of the operation. It said one or more unknown perpetrators had fired shots in the church around 9 p.m. The area has been cordoned off extensively. Motorists should avoid the area as far as possible. The danger area should be avoided. People in the danger area should stay where they are and not go outside for the time being.

Hamburg's Mayor Peter Tschentscher (SPD) called the reports "shattering". "The emergency services are working flat out to track down the perpetrators and clarify the background," he said, expressing his "deepest sympathy" to the victims' families.

Interior Senator Andy Grote (SPD) explained that the police were "on duty with a large contingent including special forces to ensure security on site and to quickly and fully clarify the circumstances of the crime".