Polish officials have shut down 13 escape room sites over safety issues after five teenage girls were killed in a fire.
Firefighter chief Leszek Suski says the escape room at a private house in the city of Koszalin where the girls died had no emergency evacuation route.
The 15-year-olds had been celebrating a birthday when they died on Friday, locked inside a room.
Firefighters found their bodies after they extinguished a fire next to the locked room.
Post-mortem examinations showed they died of carbon monoxide inhalation.
Police chief Jaroslaw Szymczyk said other people had previously posted critical remarks online about the safety of that escape room site, but local officials were not notified.
The 28-year-old who runs the site has been detained and will be questioned, Szymczyk said.
His employee, who suffered burns in the fire, will also be questioned.
Prime Minister Mateusz Morawiecki spoke after holding a meeting in which officials discussed ways to improve safety at entertainment venues.
He called the teenagers' deaths an "immense tragedy".
Since Friday, more than 200 of Poland's some 1100 escape rooms have been checked, revealing a number of safety flaws that needed to be immediately fixed.
Players in escape room games are locked inside a room or building and must solve puzzles and find clues that lead them to the key that will unlock the door.
Regarded as an intellectual challenge, the games are highly popular among teenagers in Poland.