A protest against a major rail project in southwest Germany turned violent late Monday, leaving nine police officers injured, one of them seriously, authorities said. Hundreds of demonstrators tore down a 200-metre (yard) fence at Stuttgart\'s train station, damaging construction vehicles and destroying materials \"with brute force,\" a police spokesman said. Eight officers needed hospital treatment for suspected blast trauma after demonstrators let off an explosive device, while a ninth was seriously injured after being attacked by a \"mob\", the spokesman said. The seven-billion-euro (10-billion-dollar) \"Stuttgart 21\" project aims to make the city and the region part of a 1,500-kilometre (930-mile), high-speed rail route across Europe. But a major revamp and partial destruction of Stuttgart\'s historic train station is needed, and opponents say the project will be much more expensive, potentially dangerous and do little or nothing to speed up rail traffic. Months of demonstrations and a change in the state government led to a temporary construction stop in March, but this has since been lifted as long as the work is reversible.