DEGAÑA, Spain, March 31, 2025 (BSS/AFP) - Five people died and four were seriously injured in a blast Monday at a coal mine in northern Spain's Asturias region, the nation's deadliest mining accident in decades.

Two other workers at the Cerredo mine in Degana, around 450 kilometres (280 miles) northwest of Madrid, were unharmed in the accident, local emergency services said.

It was the deadliest mining accident in Spain since 1995 when 14 people died following an explosion at a mine in Asturias near the town of Mieres.

Initial indications were that the blast was caused by firedamp, a term referring to methane forming an explosive mixture in coal mines, the central government's representative in Asturias, Adriana Lastra, told reporters at the scene.

"Police are already investigating what happened, they are already at the scene," she added.

The explosion occurred underground in the mine at around 9:30 am (0730 GMT) and as news of the blast spread, workers' families flocked to the site, which was surrounded by police and emergency services vehicles.

"It's scandalous. Companies used to guarantee safety, but they are doing it less and less," Jose Antonio Alvarez, a relative of one the miners who died, told regional newspaper El Comercio.

- 'Weight of the law' -

The five people who died were between the ages of 32 and 54, the regional government of Asturias said on X.

The injured were taken to hospitals in nearby cities, two of them by helicopter. They had suffered burns and, in one case, a head injury.

The mine is owned by a recently created local company called Blue Solving, which was trying to repurpose the site for the extraction of "high-performance minerals" for industrial use, according to local daily newspaper La Voz de Asturias.

Visiting the site of the accident, Labour Minister Yolanda Diaz vowed that the "weight of the law will fall" should anyone be found responsible for the tragedy.

"In the 21st century no one should die like this," Diaz added.

Prime Minister Pedro Sanchez sent his "sincere condolences" to the families of the victims and wished a "speedy recovery" to the injured, in a message posted on X.

The head of the regional government of Asturias, Adrian Barbon, declared two days of mourning "as a sign of respect for the deceased".

Mining has for centuries been a major industry in Asturias, a densely forested mountainous region.