Two children and a teacher were also injured in the fire that gutted the three-story building about 60 miles outside Seoul.
Â"Why did this happen to me? I can't believe it,Â" wailed Choi Sun-ju, 34, after being told her 6-year-old daughter, Jon Su-young, was dead. Her husband, Jon Hyun-jung, 41, helped steady her.
Their daughter and 18 other children from the same neighborhood kindergarten in Seoul were among the 21 youngsters and two adults killed in the fire.
About 450 kindergarten and grade school children and their teachers were attending a two-day recreational program at the camp overlooking the Yellow Sea on South Korea's west coast.
Â"This is like the sky falling on me,Â" said Koh Suk, 37, a pharmaceutical company executive who lost 6-year-old twin daughters Ka-hyon and Nam-hyon. Â"I still can see their smiling faces when they went out of the gate, saying goodbye to me.Â"
With all of the victims burned beyond recognition, teachers and center staff had to conduct a roll call of survivors before parents of the dead could be notified.
Police said an electrical short-circuit may have started the fire in a third-floor room where 19 children were sleeping, with the flames spreading rapidly.
Â"It was too hot in the room, too hot,Â" 5-year-old Kim Yoo-jung said in tears from her hospital bed. Â"My legs were burned and aching so I was brought here.Â"
Â"There were bursts of sparks in a room on the third floor and then all of a sudden I saw blazes spreading rapidly,Â" Chun Kyong-ja, a female worker at the center, said.
The fire broke out in one of three buildings at the center where the children and teachers from eight kindergartens and primary schools from nearby towns and cities were asleep, police said.
The fire spread rapidly to other parts of the building, sending hundreds of children in lower floors fleeing in confusion, they said.
Part of the building collapsed as firefighters struggled for three hours to contain the blaze.
Although police were still searching for the cause of the fire Wednesday, but CBS News Correspondent Bruce Dunning reports that South Korean media were already asking how this brand-new summer camp was able to operate.
The bunkhouse was built of shipping containers stacked up and bolted together. By the time fire crews arrived, the upper two stories were engulfed in flames. Much of the jerrybuilt structure collapsed and toxic gas from the containers apparently suffocated most of the sleeping victims.
Police said the fire broke out 30 minutes past midnight but wasn't reported for 70 minutes because the blaze destroyed the center's telephone lines. It took another hour for the first fire trucks to arrive at the ite from the nearest fire station at Osan, 43 miles away, they said.
All bodies were brought to a national scientific investigation center in Seoul for identification. Center officials said most would require DNA and forensic tests.
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