The fire broke out late on Sunday night in the building housing around 40 young girls from impoverished hill tribes in the province of Chiang Rai.

Many of the girls were asleep in their beds when the incident occurred. At least 17 girls were killed and two are still missing. Another five have been reported injured, two of them seriously.

Some people posted images of the burning school on social media.

"The fire is out, but the cause of the blaze is still under investigation," Police Colonel Prayad Singsin told the AFP news agency.

Another official said that because not all of the students were asleep, many were able to escape.

Rescue workers were still searching through the remains on Monday morning.

blc/jm (AFP, EFE)