A fire broke out during an escape room game in northern Poland, killing five teenage girls and injuring a man, authorities said.
Police said the dead were found after firefighters put out the blaze, which began around 5pm at an escape room venue in Koszalin.
Escape rooms are highly popular across the world, including Poland.
Polish Interior Minister Joachim Brudzinski said the girls were all 15 years old.
Monika Kosiec, a spokeswoman for police in Koszalin, said the victims were thought to have been celebrating one of their birthdays.
She said a 25-year-old man had been hospitalised with burns and could not be immediately questioned by investigators probing the cause of the fire.
The Polish state news agency PAP said it had learned unofficially that the girls died from carbon monoxide asphyxiation.
Footage on private TVN24 showed ambulances and fire engines in front of a detached two-storey house with a large escape room sign in front.
Brudzinski ordered fire safety controls to be installed at all escape room locations in Poland.
President Andrzej Duda said on Twitter it was a “crushing tragedy” that five young girls died so early in their lives.
Koszalin Mayor Piotr Jedlinski announced that Sunday would be a day of mourning in the city.