Five teenage girls have died after a fire broke out while they were playing an escape room game in northern Poland.
The girls, all aged 15, were visiting the attraction in the city of Koszalin to celebrate a birthday.
A 25-year-old man was seriously injured in the blaze which started at around 17:00 local time (16:00 GMT) on Friday. Leaking gas cylinders are believed to have caused the blaze.
Escape rooms have become popular in Poland in the last four years.
The authorities have ordered that all venues now be checked to ensure they meet safety standards.
What are escape rooms?
Participants are generally locked in a room and must solve a series of puzzles in order to get out.
The games are popular around the world.
The industry has grown rapidly in recent years. It is estimated there are around 1,000 in Poland.
In the UK, the number of escape rooms soared from just seven in 2013 to more than 1,000 as of last year.
What could be the causes?
The room was 7.3 sq m (78 sq ft), authorities say.
Leaking gas cylinders used to heat the building started a fire in the adjacent waiting room, a prosecutor said.
Flames and toxic smoke spread quickly and firefighters used specialised equipment to break in, but it was already too late.
The teenagers are believed to have died of asphyxiation.
How have officials reacted?
Polish President Andrzej Duda said the fire was an "appalling tragedy".
"Five joyful girls starting out in life have had life torn away from them," he wrote on Twitter. "May God protect their parents and loved ones."
Interior Minister Joachim Brudziński shared his condolences.
"I want to express my sympathy and regrets to the families of the victims of the fire," he said in a tweet.
"I've instructed the chief commander of the State Fire Brigade to carry out fire checks on all places of this type across the country," he added.
The mayor of Koszalin, Piotr Jedlinski, has declared Sunday a day of mourning in the city.