The start of the Oktoberfest in the southern German city of Munich next Saturday has been overshadowed by a tragic accident after a worker was fatally injured during a test ride on the Olympia Looping roller-coaster. The fire brigade in the southern city of Munich, which hosts the world-famous folk festival every year, said a 20-year-old was hit by a wagon at full speed and left seriously injured under the rails. The worker was treated at the Oktoberfest site in the Bavarian capital, it said. Emergency services carried out resuscitation measures on the way to hospital, where the man died. The …