PHNOM PENH (AFP) - The death toll from a massive stampede at a festival in Cambodia soared above 450 Wednesday as an initial investigation pointed to overcrowding and fears of a bridge collapse as the likely cause. The government admitted it had overlooked issues of crowd control, while the victims grieving relatives expressed growing anger about security at the event, which attracted some three million revellers from all over Cambodia. We were concerned about the possibilities of boats capsizing and pick-pocketing. We did well, but we did not think about this kind of incident, government spokesman Khieu Kanharith told AFP. The authorities said the throngs of revellers crossing to one of the main festival sites on an island in Phnom Penh had panicked as rumours spread through the packed crowd that the bridge was about to give way. The deaths happened because the bridge was overcrowded and there was panic that the bridge was collapsing because it is hung by cables and it was swaying, said Prum Sokha, who is heading a panel investigating the tragedy. Some started screaming that the bridge was collapsing, that people were getting electric shocks and that the iron cables were snapping, so the people pushed each other and fell down and the stampede happened. The people had nowhere to run, said Sokha, secretary of state at the Ministry of Interior. Officials said a private firm had been in charge of security on the island and the bridge where the disaster unfolded at the annual water festival. The place is private, so they used their own security, and police only helped handle order outside, Kanharith said. As the first funerals and cremations began taking place across the country, bewildered relatives searched for answers. I feel very sad and angry about what happened, Phea Channara said at a funeral service for his 24-year-old sister on the outskirts of Phnom Penh. I wonder if the police really did their job. Why did they allow it to happen in the first place? Waiter Choy Bora said he was frustrated with the security response as he watched the clean-up operation of the bridge which had been littered with discarded flip-flops, items of clothing and water bottles after the crush. I am very sad about this incident and also angry with the authorities. They have not done their job properly, said the 22-year-old. At the entrance to the now notorious crossing, still closed off to the public, locals in the mostly Buddhist country burned incense and prayed for the souls of the deceased. They laid out flowers, cake and bananas as offerings. Prime Minister Hun Sen has described the disaster as Cambodias worst tragedy since the Khmer Rouges 1975-1979 reign of terror, which killed up to a quarter of the population. Thursday will be a national day of mourning. The prime minister also said that a memorial stupa will be built to commemorate the souls of the people who lost their lives in the incident... and to remember the serious tragedy for the nation and the Cambodian people. Social Affairs Minister Ith Samheng told AFP the toll from the tragedy had jumped to 456 dead and 395 injured, revising the previous figure of 378 dead. Some bodies were transported home straight away and some injured people died at home, he said, explaining the increase. Exuberant festival-goers had been crossing the bridge to reach an island hosting concerts, food stalls and ice sculptures when the stampede began, resulting in a deadly crush. In scenes repeated across the city, the dead were laid out in rows under a white tent erected in Calmette Hospital car park, their uncovered faces showing that many had suffered bloody bruises during the stampede. Military trucks later began delivering the victims to their relatives and by Wednesday morning all bodies had been returned home, the health ministry said. The stampede marked a tragic end to the boat races, concerts and fireworks that are traditionally part of the annual festival to celebrate the reversal of the flow between the Tonle Sap and Mekong rivers.