Ten people were injured in a knife attack at a school in Ostroleka in northeastern Poland on Wednesday, the town’s mayor said, with police detaining the 19-year-old suspect, who was among those hurt, shortly after the incident. Masovian Regional Governor Mariusz Frankowski told reporters that nine people had been taken to hospital but that none of them was in a life-threatening condition. “The injured included five students, two teachers and two bystanders, as well as the perpetrator, who...