The boy then seriously wounded himself.
The stabbing took place at the Tunagården treatment centre in east Malmö at 9.20pm on Sunday night.
For reasons that remain unknown, the 15-year-old boy attacked his 44-year-old caregiver with a knife.
The woman was so severely injured that she died on the scene twenty minutes later.
Following the attack, the boy then cut himself.
“He’s had surgery and is being treated for serious injuries to his stomach. But his condition isn’t life threatening,” said Hans Nilsson of the Skåne police to news agency TT.
The boy, who comes from southern Skåne, has been detained on suspicion of murder or manslaughter.
Because there were no witnesses to the incident, the police don’t know the events leading up to the stabbing.
What is clear is that a staff member found the caregiver and the boy after the attack and then called police.
“We won’t know about the circumstances until we can talk to the boy. And we can’t do that until he wakes up. Perhaps later today,” said Nilsson.
The Tunagården facility takes in boys and young men placed there by social services or under the Child Welfare Act. The target group consists of boys between 14- and 21-years-old who have committed sexual assaults.
Bengt Hansson, head of Tunagården, told TT that staff and the eight other boys being treated at the facility are in a state of shock following the stabbing.
“There is total panic. It’s terrible, it can’t be any worse,” he said.
A crisis group has been called in to help care for those affected.
Entrance to the facility, which is operated by the National Board of Institutional Care (SiS), has been blocked, and operations moved to a nearby location, according to Hansson.
According to the Malmö University Hospital, the boy is seriously injured and will be remain in hospital for further care. However, his injuries are not life threatening.
Ewa Persson Göransson, head of SiS, was reached late on Sunday.
“It’s an extremely tragic incident. We’re now doing all we can to get more information about what happened. We’re also getting support to the woman’s family, staff, and the boys who remain in the facility,” she told TT via press secretary Cecilia Sandahl.
According to the SiS website, Tunagården has nine spaces. In addition to those who assist with treatment, the center also employs to teacher.
Those living at the center receive school lessons and go through regular therapy.