Officials said 16 people died on the scene on Saturday afternoon and a further three died of their injuries during the evening and overnight. More than 340 people are reportedly injured, many of them seriously.
The deadly incident has sparked questions about the crowd management and safety concept of organisers, while an investigation has been launched to try to determine the cause of what is being called a catastrophe.
An estimated 1.4 million people attended the free techno music festival in the Ruhr city of Duisburg, and as always, the Love Parade was proceeding peacefully.
Problems began to develop on the way to the disused freight railway depot where the final party was to be held. The huge crowd had been directed along two different routes to get there, but these merged into a low-built tunnel – the entrance and exit to the depot.
There an enormous pressure began to build as people pushed forwards to get through the tunnel. Early reports suggested that organisers had at least partly blocked off the exit of the tunnel into the large space on the other side as it was already overfilled.
People started fainting and collapsing inside the tunnel, which reports say grew very hot. This prompted many to try to avoid the tunnel altogether and climb up a stairway and a wall. When a number of people who had adopted this tactic fell into the crowd panic broke out.
Police and ambulance crews were unable to get into the tunnel to try to pull injured people out as it was simply rammed full of people unable to move forwards or backwards – eyewitnesses reported desperately trying to remain on their feet in fear that they would be crushed or trampled.
Emergency services took hours to reach everyone who needed attention and hearses were leaving with bodies until midnight.
Organisers did not cancel the party, fearing further panic, so the hundreds of thousands of ravers who had already got into the party continued to dance to the DJs who carried on playing. Only when word of the disaster started to spread did people begin to leave, finding the emergency exits had been opened and buses had been stationed to help them get home.
As the investigation began on Sunday, questions arose about why only one entry and exit point had been set up to an area which could hold a maximum of 250,000 people – particularly when more than a million were intending to attend.
The Love Parade, which began as a politically-motivated march in Berlin in 1989, has turned into what is often billed as the world's biggest techno party. It left the German capital in 2007, and was afterwards organised in various towns in the Ruhr area.
Last year Bochum failed to find a suitable venue, and the party did not take place. This year it was billed as one of the biggest events of the Ruhr.2010 culture capital festival.