Police say knife attacker injures 4 at Oslo school -- report

OSLO, March 19 (Xinhua) -- A knife-wielding attacker injured four school employees in Oslo, Norway, on Tuesday, media report quoted Police source as saying.

According to the report, Police said they have arrested the attacker. The four injured, a teacher and three other staff members, have been taken to the hospital.

The motive of the attacker remains unclear, the report said.