Police are currently investigating the incident, which took place in Karlstad.

“In conducting the intervention, we were forced to use some force to subdue him,” Värmland police spokesman Tommy Lindh told news agency TT on Thursday.

According to newspaper Aftonbladet, the man was forced down onto his stomach during the intervention over the weekend. On the way to the hospital, his heart stopped. On Tuesday, the man died of injuries caused by the cardiac arrest.

“The man was taken into custody because he was disturbed and posed a danger both to himself and others. He was very agitated and violent,” added Lindh.

According to Lindh, the man had not attacked anyone, and that he was mainly trying to harm himself. However, he declined to divulge further details about the incident.

“There is an ongoing internal investigation,” he explained.

According to the Aftonbladet daily, the man lay on his stomach in police bus. Police would not comment on the newspaper’s claims, citing its own preliminary investigation.

The man was taken to hospital where he later died. Lindh declined to disclose exactly when the man died.

“We received information from the hospital yesterday [Wednesday] that he had died,” he said.

The internal inquiry, conducted by police in Västerås, is headed by prosecutors in Gothenburg.