The police officer, who was 32, was shot as he attempted to detain the man in central Nyköping, 100 kilometres south of Stockholm. Police were enforcing an order from mental health authorities to section the 55-year-old man.
The policeman, who was wearing plain clothes at the time, was shot in the hall of the apartment block in which the man lives. He was hit in the chest and abdomen. His 27-year-old colleague was hit in the arm, and his injuries were reported by Nyköping hospital not to be serious.
A large police force was sent to the scene, on Östra Kyrkogatan, following the shooting. Police were able to overpower the man with use of pepper spray.
Many question marks remain over the killing. Several shots were fired during the incident, but police were not saying on Thursday morning whether the police officers had also fired shots.
“We want to hold back information for a little while longer. We will give further information about the progress of the investigation later in the morning, and then it will be clearer which details we can release,” said Ulf Göransson, spokesman for Sörmland Police.
Police will continue to question witnesses on Thursday morning. The crime scene remains sealed-off.
Johan Levin, a senior officer in the investigation, said that the man had lived in the apartment block for a long time. Police have seized a handgun, believed to be the murder weapon. The man is suspected of murder and attempted murder.