“Armed police came running in with dogs,” said bystander Kalle Ekström to the Aftonbladet newspaper.
Police cars and helicopters swarmed the scene early on Monday afternoon after a woman was shot and injured in a suburb north of Stockholm.
“They said that someone had been shot in the apartment upstairs,” Ekström said.
Police has arrested one man in connection with the shooting, which has been labelled as attempted murder, yet have not yet confirmed if just one perpetrator is responsible for the attack.
Meanwhile, three others have been taken in for questioning, although police have not confirmed whether these people are suspected of involvement in the attack or are witnesses.
“These are people who we believe have information they can offer us,” said Towe Hägg of the Stockholm police to the paper.
Police have launched an investigation and are currently calling for witnesses to come forward.
Traffic in the area was stopped following the attack, including nearby commuter trains, although by 1.30pm normal traffic flow resumed.
Meanwhile, the victim of the shooting is being cared for at the Karolinska University Hospital in northern Stockholm.