The girl remained conscious and has been taken to Karolinska University Hospital where she is being treated for serious injuries.
“According to the information I have received, and this isn’t absolutely certain, the girl is 16 years old,” said police spokeswoman Mona Johansson.
Police said they are searching for a perpetrator thought to be the same age as his victim.
“We have put out a lot of units, we have criminal investigators interrogating people, and we have put up a helicopter,” said Johansson.
Police have launched a preliminary investigation and are classifying the attack as attempted murder.