At least 51 people have been killed and more than 118 injured in a nightclub fire in North Macedonia, officials say.

The blaze broke out around 02:30 (01:30 GMT) at the Pulse club in Kocani, a town around 100 km (60 miles) east of the capital, Skopje.

As many as 1,500 people were attending a concert by DNK, a popular hip-hop duo in the country, when the fire started. Footage posted on social media shows the roof of the building engulfed in flames.

Prime Minister Hristijan Mickoski called it a “difficult and very sad day” for the country which had now lost so many “young lives.”

Interior Minister Pance Toskovski said initial reports suggested the fire started from sparks caused by pyrotechnic devices.

Speaking outside the Kocani police station, he said the sparks had hit the ceiling, which was made of highly flammable material.

Footage shows the band playing on stage when two flares go off, sparks then catch on the ceiling before rapidly spreading.

Toshkovski said one man had been arrested, though he did not provide further details on his involvement.

Kocani’s hospital initially reported 90 admissions, with many suffering severe burns. Some of the injured have since been transferred to hospitals in Skopje for further treatment.

The health minister said 18 remained in critical condition.

Kocani’s hospital director Kristina Serafimova told local media that staff had struggled to identify patients due to a lack of ID cards. However she went on to say that those deceased were aged between of 14 and 24.

A team of investigators has begun looking into the incident.

In a statement, the prime minister said the government was “fully mobilised and will do everything necessary to deal with the consequences and determine the causes of this tragedy.”

DNK was formed in 2002 and has topped the charts over the past decade.