The principal of the Källskolan school in Kungsängen in northern Stockholm was stabbed repeatedly in the back in the school staffroom. The incident, which took place shortly before 1pm, was witnessed by several other teachers.
Police dogs and helicopters were quickly brought in to aid in the search for the perpetrator.
The suspect, who is known to police, was nowhere to be found when police raided his home address in Kungsängen at around 3pm.
The man had returned home for a quick change of clothes but soon took off again in a red car, according to Dagens Nyheter.
At around 5.30pm he change clothes again before leaving his car and making his way towards Central Station, the newspaper reports. There police were able to make an undramatic arrest.
The head teacher was not seriously injured in the attack, according to staff at Karolinska University Hospital.
The school’s deputy headmaster, Claes Bystedt, spoke to the principal before he was taken away in an ambulance.
“He said that he had been stabbed but his condition was stable when he left here,” Bystedt told TT.
“We were aware of a threat. The guy was here earlier in the week making threats,” he added.
According to the deputy headmaster, the principal was stabbed seven or eight times in the back, he said.
The suspect is believed to be related to a pupil at the school, Dagens Nyheter reports.
Claes Bystedt said that the perpetrator had never attended the small private school, which has a Christian profile. The school is attended by 140 pupils between the ages of six and sixteen.