At least 51 people were killed and another 100 injured when a fire broke out overnight in a nightclub in North Macedonia, Marija Miteva, a government spokeswoman, said on Sunday.

The country’s interior minister, Panche Toshkovski, told a news conference that the blaze had broken out during a pop concert at the club in the eastern town of Kocani. He said that fireworks had been set off, causing the roof to catch fire.

“This is a difficult and very sad day for Macedonia,” North Macedonia’s prime minister, Hristijan Mickoski, wrote on X. “The loss of so many young lives is irreparable, and the pain of the families, loved ones and friends is immeasurable.”

Details of the blaze could not be independently confirmed. The town is about 50 miles east of the capital, Skopje.

The office of the government’s public prosecutor said in a brief statement that officials in Kocani were still working to assess the number of victims.

Angela Aggeler, the American ambassador to the country, wrote on X, “My heart breaks this morning for the many victims in last night’s fire at a nightclub in Kochani.” She added, “The loss of so many young lives in one community is a terrible tragedy.”

This is a developing story.

Alisa Dogramadzieva contributed reporting from Belgrade.