Parents rushed to an elementary school in Thailand Monday, where 18 girls were killed overnight in a fire at their school dormitory.

“It is still very chaotic here,” the school’s manager Rewat Wassana told CNN. “We are in the process of identifying bodies, none of the parents can claim their children’s bodies yet,” he said.

Thirty-eight children – all girls between the ages of 5 and 12 – were sleeping in the dorm when the fire broke out at the private Pitakiatwittaya School Christian elementary school in Thailand’s northern Chiang Rai Province, according to lead investigator, Police Captain Kachornsak Pongthit.

It’s not clear what caused the fire, which is believed to have started around 11:00 p.m. local time Sunday (12 midnight Saturday ET).

Twenty girls were rescued after firefighters on ladders scaled the walls of the building, said Sawang Momdee, chief of Chiang Rai’s fire unit, who led the operation. Of the 20 rescued, five were injured.

“We were trying to save everyone through the window, but the fire spread very quickly,” he said. “We have done our best.”

In a message on its Facebook site, the school, which is known for providing free education to hill tribe children, posted an image and said the school would be closed until Friday due to the blaze.

The school has been operating for five years and teaches 142 students from pre-elementary to grade 6.

About 60% of the students were poorer children from surrounding villages who had been receiving free education and accommodation from the Christian charity.

•Photo shows firefighters battling to quench the fire at Pitakiatwittaya School Christian elementary school in Thailand’s northern Chiang Rai Province.

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