The officer was stabbed in the stairwell of a metro station at Medborgarplatsen, officials said.
His colleague seized the attacker who has now been arrsted.
The entire square, which is popular with tourists, and a nearby nursery were sealed off by officers.
Witnesses on social media said the attacker “snuck up behind the policeman” and stabbed him “unprovoked”.
One witness saw police tackle the suspect.
She said: “I got above ground from the subway when the police seized a man, he appeared to be aged 30.”
Another witness said: “An ambulance has been here … it is unclear if it was with the police officer who was hurt.”
One witness saw police tackle the suspect.
She said: “I got above ground from the subway when the police seized a man, he appeared to be aged 30.”
Another witness said: “An ambulance has been here … it is unclear if it was with the police officer who was hurt.”
The sealed-off nursery is attended by 70 children, officials said. There are no indications the building was in danger.
The metro is no longer stopping at Medborgarplatsen station. The No. 3 bus line to Sodersjukhuset has also been diverted.
http://www.express.co.uk/news/world/848 ... n-stabbing