German media reported that as many as 1.4 million people showed up to the Love Parade, where a mass panic Saturday left 19 people crushed to death and 342 injured. Police blamed organizers and officials in Duisburg, an industrial city that gave the world's largest techno music festival a home after it was driven from Berlin because of noise and overcrowding.
Witnesses, however, blamed police and private security staff, saying the panic broke out after they closed the end of a tunnel - the only entrance to the festival grounds - when the venue became too full. Police denied that and said they actually opened a second exit to disperse the masses before the accident happened.
It remained unclear Sunday what exactly triggered the panic, but it appeared that several people trying to escape the pushing crowds climbed up a steep metal stairway on a ramp in front of the tunnel and fell into the crowd. Amateur video footage showed thousands of festivalgoers crammed wall to wall, with some trying desperately to climb out.
Police said nobody was killed inside the tunnel itself.
Since the event was free, even the number of people who attended may never be known. Police did not confirm the 1.4 million estimate and suggested that it was much lower based on the fact that the railway service registered 105,000 as arriving in the city by train in the preceding hours.
One thing is clear: The Love Parade is no more. Organizer Rainer Schaller said it will never be held again out of respect for the victims.
"The Love Parade was always a peaceful event and a happy party," but would forever be overshadowed by the tragedy, Schaller said at a news conference. He promised to cooperate with authorities who have launched an investigation.
Witnesses described a desperate scene, as people piled up on each other or scrambled over others who had fallen. TV images showed huge masses of people packed inside the wide tunnel and people struggling to escape up an embankment when the chaos broke out.
City officials chose not to evacuate the site, fearing it might spark more panic, and many people continued dancing, unaware of the deaths. Rescue workers carried away the injured as techno music thundered in the background.
Police said those killed were between the ages of 18 and 38 and include several foreigners, among them Spaniards, an Australian, an Italian, a Bosnian, a Chinese citizen and a person from Holland.
Rainer Wendt, the head of a key national police union, told the Bild daily newspaper that the city and organizers are to blame.
"I already warned a year ago that Duisburg is not a suitable place for the Love Parade," Wendt said. "The city is too small and narrow for such events."
Duisburg is a city of 500,000 in western Germany's highly industrialized Ruhr region known for its coal mining and steel production. The region's economy has declined in recent years and it has been trying to bolster its image on the cultural scene. The entire Ruhr region is the European capital of culture in 2010.
The original Berlin Love Parade grew from a 1989 peace demonstration into a huge outdoor celebration of club culture that drew about 1.5 million people at its peak in 1999. But it suffered from financial problems and tensions with Berlin officials in later years, and eventually moved.
According to media reports, local police and firefighters expressed concerns early on about whether Duisburg was big enough to host over up to a million people or more, many of them possibly under the influence of alcohol or drugs.
A high-ranking firefighter warned the city's mayor in a letter in October 2009 against holding the event at the old freight railway station "because the place is not big enough for all the people," the daily Koelner Stadt-Anzeiger reported.
On the Internet portal Der Westen, which is run by several regional news outlets, readers also voiced concern ahead of the parade.
A physics professor who studies mass crowd behavior at the university of Duisburg-Essen, and who had examined the concept for the Love Parade for the city ahead of the event, said it was too early to say what exactly had caused the tragedy.
"The security concept seemed plausible, but of course, we don't know if security personnel in and before the tunnel acted according to the concept," Michael Schreckenberg told The Associated Press. "Also, one does not really expect people to fall into the crowd from above."
A day after the tragedy, the tunnel - still strewn with trash and metal barriers overturned in a panic - was a site of mourning. Amid the candles, flowers and written notes just outside one end of the tunnel was a cardboard sign simply asked "Why?"
Chancellor Angela Merkel expressed shock at the "horrible, sad" turn of events and said everything must be done to ensure such tragedies don't repeat themselves.
"I think we need an intense investigation now into how this happened," she said Sunday in Bayreuth, where she was attending the opening of the yearly Wagner music festival. "We must do everything to prevent this from being repeated."
Pope Benedict XVI said he learned of the tragedy in his native Germany "with profound pain" and said he was praying for the victims and their loved ones.
The founder of the Love Parade, Matthias Roeingh, a techno DJ generally known by his artist's name, Dr. Motte, called it a scandal that revelers were all funneled through a single tunnel under a highway onto the festival grounds.
"It's all about making money," he said in comments carried by the Berliner Kurier daily. "The organizers didn't show even the slightest sense of responsibility for people."
Grieshaber reported from Berlin. Associated Press Writer Vanessa Gera in Berlin contributed to this report.