Five teenagers celebrating a birthday were killed in blaze that broke out at an escape room center in the city of Koszalin, Poland, on Friday.
Flowers and toys were laid out at a vigil held to remember the fallen friends, all age 15, as hundreds of mourners turned out over the weekend.
Escape rooms, in which players solve puzzles in a limited amount of time to unlock a door, have become popular around the world. But when a fire ignited at the facility in Koszalin, the teens became trapped in the locked room and died. Others were injured.
Prosecutors said it's believed a leaky gas container inside a heater may have caused the fire.
As a result of the conflagration, authorities have shut down 13 other escape rooms around the country and flagged more than 100 to be unsafe. The country's prime minister, Mateusz Morawiecki, also said a review will be carried out to determine if new safety regulations are needed.