Police in the northern German town of Wedel, near Hamburg, are continuing to search for a motive after a teacher was stabbed outside an adult education centre on Friday. A police spokesman told dpa that a 67-year-old man was critically injured in the attack, which took place in the centre’s car park. Two suspects were arrested on the grounds of the centre after a short manhunt. Authorities said the pair are brothers from Syria aged in their early 20s. The background to the offence is still unclear, but it is being assumed that the victim and perpetrators knew each other, as the teacher was rep…