At least 13 people were killed in a fire in a Spanish nightclub on Sunday morning, authorities said, with four more reported injured.

Search and rescue work was still ongoing at the club in the southeastern city of Murcia, according to the city's town hall.

Emergency services said in a statement on social media that rescuers had managed to enter the building after first being alerted at 6:00 am local time (0400 GMT) that a fire had broken out in the nightclub.

They finally managed to enter around 0800 GMT and discovered four bodies, then two others around forty minutes later.

Later, the police confirmed the toll had risen to 13.

According to photos released by emergency services, the fire broke out in the "Teatre" nightclub, also called "Fonda Milagros". The photos showed water hoses from fire trucks still spraying the blackened facade of the club.

Thick smoke could be see billowing from the roof of the building.

"Emergency services are still hard at work to put out the fire that occurred in the Teatre nightclub," the city's town hall said, adding it "deeply regrets" the accident and offering condolences to those affected.

Four others were injured, two women aged 22 and 25 years old and two men in their forties, all suffering with smoke inhalation.

The Mayor of Murcia, Jose Ballesta, announced three days of mourning.

He said more than 40 firefighters and 12 emergency vehicles were attending the scene.