As it soon turned out on the spot, police officers had shot at a 31-year-old man who was armed with a knife. The police had previously been alerted because a person had been rampaging in a facility for drug addicts. According to the General-Anzeiger, the emergency call had been made by the crew of an ambulance who had been called to the house because of an internal emergency. In view of the threat, the rescue workers retreated into the ambulance. According to eyewitnesses, a patrol car was on the scene within a very short time.

"The control centre had been informed at around 9.50 a.m. via the emergency call that a man was showing conspicuous behaviour in a residence on Kaiserstraße and was also armed with a knife," the Bonn police later described the trigger for their deployment.

When the officers arrived with the patrol car, there was an "acute threat situation" against the police officers themselves: "The 31-year-old approached the officers with a knife. The police officers demanded several times that the man stop and put down the knife," said a spokesperson for the authorities. The 31-year-old did not comply with this request and a warning shot did not stop him either, he said. "In this threatening situation, an officer fired several shots from his service weapon," the press office said. Mark Wassong, an employee of a neighbouring hair salon, told the General-Anzeiger shortly after the incident that he heard four or five shots around 10 am. The attacker was hit in the leg and, after receiving emergency first aid, was taken to hospital seriously injured. According to the police in the afternoon, his life is not in danger.

The incident between the railway line, road traffic, cyclists and parked cars became even more explosive due to the fact that there is a kindergarten right next door. Shortly after the incident, the police announced on Twitter that there was no danger for residents: the situation was under control. Meanwhile, the parents of the children cared for in the daycare centre were informed about the incident by its management. "We were told that something had happened near the day care centre. But we were also told directly that all the children were fine and nothing had happened inside the day care centre itself," reported a father at the scene. The children could be picked up by their parents at noon. Other parents also expressed relief that nothing had happened to the children and praised the communication of the day-care centre staff.

Cynthia Rühmekorf, spokesperson for the Association for Assistance to the Vulnerable (Verein für Gefährdetenhilfe, VFG), which also runs the day care centre on Kaiserstraße, confirmed the account of what happened. According to Rühmekorf, the facility in question is the adaptation facility "Ausweg", which offers inpatient help to people with addiction problems. According to the VFG homepage, the offer is aimed at people who are addicted to illegal drugs, alcohol or medication and have completed an inpatient withdrawal treatment.

The press spokesperson did not answer questions about the 31-year-old, such as whether the violent outburst had come out of the blue or had possibly been announced. The institution itself did not want to comment on details when asked. However, Cynthia Rühmekorf confirmed that they were "very happy" that the two staff members who had been in the facility were unharmed: "They are fine, they are well", said Rühmekorf. Both had run into the street on the occasion of the man's violent outburst.

The affected section of Kaiserstraße remained completely closed during the day. Traffic, including bus lines 610 and 611, were diverted via Adenauerallee.