Lieutenant General Sok Phal, deputy chief of the National Police and vice-president of the special committee for the accident investigation, said on Wednesday the primary assessment was, after inspecting the site and talking with victims and eyewitnesses, that the swinging of the bridge is the cause of the accident.

A man mourns near the bodies of the stampede victims in Phnom Penh, Cambodia, Nov. 23, 2010. At least 339 people were killed in a stampede on Monday night as millions of Cambodians celebrated the annual water festival in the capital Phnom Penh, Cambodian Prime Minister Hun Sen said on state TV early Tuesday. The accident took place on a bridge that connects the city with the Diamond Island which has become the center of celebrations. [Xinhua/Phearum]

"It's a kind of suspension bridge, but people were not aware of it and when it (the bridge) swung, some four or five people on it felt dizzy and fainted, which triggered a rumor that the bridge was collapsing," said he, adding that the bridge in fact was in good condition.

Sok Phal said that the deaths were from suffocation and stampede, ruling out the possibility of terrorism or electrocution.

A government official who requested not to be named, however, said Tuesday that it was a lesson learned for Phnom Penh authorities and police as well as medical staff to be well prepared for such important and large event.

"During such large and important event, the authorities must have evacuation plan, fire lane and standby medical team," he said, adding that few precautions were taken before and during the event.

The official estimated there were about 20 to 25 people were fully packed in a square meter on the bridge just before the accident happened.

The police teams seemed not to pay enough attention to human flow control. A Westerner who crossed the bridge in the first day of the festival wrote that "the closest security I could find were occupied making sure none of the crowds sat on the wall of the casino (Naga Casino near the bridge)," and the nearest police were busy with manning road blocks and collecting money from motorists entering designated pedestrian areas.

Accident is nothing new for Cambodia's water festival. The last time the festival saw a tragedy was in 2007, when five Singaporeans were killed after their dragon boat, carrying 22 men, capsized at the end of a race. Seventeen Singaporeans were also injured in the accident.