Investigators are working to determine cause of the blaze that broke out at facility in Tuzla in northeastern Bosnia.

A fire at a retirement home in northeastern Bosnia has killed at least 11 people and injured about 30 others, officials said.

It remained unclear what caused the blaze, which engulfed the seventh floor of the building in Tuzla, about 80km (50 miles) northeast of Sarajevo, after it broke out on Tuesday evening.

The fire, which took about an hour to bring under control, sent flames and smoke pouring out of the building into the night sky.

Bosnian media reported that higher floors in the complex were occupied by elderly people who could not move on their own or were ill.

“I had gone to bed when I heard a cracking sound. I don’t know if it was the windows in my room breaking,” resident Ruza Kajic told national broadcaster BHRT on Wednesday.

“I live on the third floor,” she said. “I looked out the window and saw burning material falling from above. I ran out into the hallway. On the upper floors, there are bedridden people.”

Admir Vojnic, who lives near the retirement home, also told the Reuters news agency that he saw “huge flames and smoke, and elderly and helpless people standing outside” the building.

Investigators were still working to determine the cause of the fire and identify those killed in the blaze, prosecutor spokesperson Admir Arnautovic told reporters.

“The identification of the bodies will take place during the day,” Arnautovic said.

Meanwhile, the retirement home’s director said he had offered his resignation.

“It’s the only human thing to do, the least I can do in this tragedy. My heart goes out to the families of the victims,” Mirsad Bakalovic told the Fena news agency.

“Last night was a truly difficult event, a tragedy not only for the city of Tuzla, but for all of Bosnia.”

Officials from across government in Bosnia and Herzegovina offered their condolences and help to the Tuzla authorities.

“We feel the pain and are always ready to help,” Savo Minic, the prime minister of the country’s autonomous Serb Republic, wrote on X.