Rescuers searching for people unaccounted for after the blaze hits a row of nightclubs popular for birthday celebrations.

The fire ripped through adjoining nightclubs in Murcia in southeast Spain on Sunday, emergency services said, adding that rescuers were still searching for people unaccounted for after the blaze.

Emergency services posted on X, the social media platform formerly known as Twitter, that firefighters were continuing to work at the scene and had not ruled out “the possibility of finding more victims”.

Jose Ballesta, mayor of Murcia, said the fire had broken out at around 6am local time (04:00 GMT) and was “extremely serious”.

Ballesta told reporters at the scene “there are still bodies to be pulled out” from the rubble, which he said was a complicated task given the “risk of collapse”.

Diego Seral, of Spain’s National Police, told reporters the dead were found in the Fonda nightclub, one of three adjoining clubs, which had sustained the majority of fire damage, including the collapse of its roof.

The collapse was making it hard to locate victims, and it was also difficult to pinpoint yet where exactly the fire started, he said.

The identification of the bodies would take time, Seral noted.

The cause of the blaze is being investigated.

Outside the club, young people hugged, looking shocked as they waited for information.

“I think we left 30 seconds to one minute before the alarms went off and all the lights went out [and] the screams saying there was a fire,” said a survivor, who was not identified.

“Five family members and two friends are missing.”

Photos released by the emergency services show water hoses from fire trucks spraying the blackened facade of the club. Thick smoke could be seen billowing from the roof of the building.

Authorities said four people were injured: two women aged 22 and 25, and two men in their 40s, all suffering from smoke inhalation.

A spokesperson for the Teatre nightclub, Maria Dolores Albellan, told reporters the fire originated in the neighbouring club, Fonda, before spreading to the two adjoining clubs.

Spanish media reported several birthday celebrations were taking place at the time.

Ballesta declared three days of mourning in the city to remember those who died. Flags were lowered to half-mast outside Murcia’s City Hall.

Prime Minister Pedro Sanchez voiced “solidarity with the victims and relatives of the tragic fire in a Murcia nightclub”.

Forty people were injured in 2017 in a packed nightclub on Spain’s holiday island of Tenerife when a floor collapsed.

In 1990, 43 people died in a fire at a nightclub in Spain’s northeastern city of Zaragoza.