By Fiona Fleck

BONN (Reuter) - Germany plunged into anxious soul-searching Monday over an annual punk festival that turned into an orgy of violence, injuring hundreds and leaving part of Hanover looking like a war zone. Three nights of vicious clashes between the punks and German police in the northern city injured policemen and punks and caused extensive damage. A headline in the Sueddeutsche Zeitung daily reflected national bewilderment: ``Hanover, Why?'' Calls for official heads to roll marked a bitter dispute over what exactly had happened. About 2,000 punks from across Germany rampaged violently at their annual gathering known as ``Days of Chaos.'' More than 2,000 police from across the country were deployed to rein them in. Beer-swilling punks -- some skinheads, some rainbow-haired, wearing dog collars and leather cuffs -- lobbed home-made firebombs and looted as police lines pushed them back with shields and batons. Despite their helmets, shields, armor and batons, 179 police officers were hurt. It was unclear how many punks were injured, but about 34 of them were taken to the hospital. ``It's like a siege,'' said a woman resident of the battle scenes at a festival with anarchist overtones that allows German youths to let off steam on a hot midsummer weekend. The chaotic festival has been an annual event over the last 11 years. Police trade union leaders called for the resignation of the interior minister of Lower Saxony state, Gerhard Glagowski. They said officers had been sent out to be stoned by a raging mob. In Bonn, Interior Minister Manfred Kanther accused regional authorities of putting public safety at risk and called for a unified security policy at national and regional level. ``Hundreds of police were sent at great risk to their safety to take the consequences for the irresponsibility of (Lower Saxony premier Gerhard) Schroeder and Glagowski, the (Social Democrats') political leadership,'' Kanther said in a statement. ``A whole section of the city was devasted by mobs who terrorized residents and damaged their property,'' he said. Glagowski, showered with criticism from conservative adversaries, said he had no intention of resigning. He defended the weekend police operation that used water cannon and baton charges to quell punks running amok. He told German NDR radio that officers had been astounded by the youths' readiness to use violence. ``We should reflect on how it came about that such readiness for violence is present in Germany. We must not confuse perpetrators with their victims.'' Germans were baffled as to how a police operation planned to ``de-escalate'' violent clashes between police and punks could have backfired quite so disastrously. ``What was planned as a de-escalation turned into a way of promoting criminals. And that was what the police did not realize soon enough. The question is, why?'' the Sueddeutsche Zeitung said. A commentary in the Frankfurter Allgemeine Zeitung daily debated the ``questionable middle road'' between tolerance and prevention in the weekend police operation. Police detained 2,000 people between Thursday and Sunday. Fourteen remained in investigative custody Monday. Punks who called a news conference late Friday after a second night of clashes said they had been provoked by an excessive police presence at an event which had never previously flared into violence on such a scale. ``We built the barricades to protect ourselves from the police. The police provoked us,'' said one punk from Hanover, who did not give his name. ``The way they were dressed, they were ready for deaths.''