As an investigation is launched into the deadly stampede at a German music festival, questions are being raised as to who is to blame.

19 people died and 342 were left injured following the deadly stampede at the Love Parade on Saturday. Media reports say as many as 1.4 million people showed up to the event at an old freight railway station which was thought to only be able to hold 300,000 people.

Police have blamed organisers and officials in Duisburg, an industrial city that gave the world's largest techno music festival a home after it was moved from Berlin because of noise and overcrowding.

Witnesses, however, are blaming the 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 have denied that and say they actually opened a second exit to disperse the masses before the accident happened.

It remains unclear what exactly triggered the panic, but several people tried to escape the pushing crowds by climbing up a steep metal stairway on a ramp in front of the tunnel and then fell into the crowd.

The tunnel, now cleared of debris and metal barriers is now a site of mourning. Amid the candles, flowers and written notes just outside one end of the tunnel was a note that simply asked "Why?"

Police say those killed were 18 to 38-years-old and include several foreigners, among them Spaniards, an Australian, an Italian, a Bosnian, a Chinese citizen and a person from the Netherlands.

Since the event was free, even the number of people who attended may never be known. As a result of the tragedy, organisers have said the Love Parade will never be held again out of respect for the victims.