The Astún resort in the Spanish Pyrenees, where the incident happened, was closed as rescue services attended the scene.

A pulley failure appears to have caused a cable to slacken and some chairs to drop to the ground, throwing skiers into the snow.

Prime Minister Pedro Sánchez said he was “shocked” by the news of the incident.

Initial reports said 30 people had been hurt, but local media later reported that 17 needed medical attention.

Ambulances and helicopters took some of the injured to hospital. Two women, both aged 18, are in intensive care, El Pais newspaper says.

According the state broadcaster TVE a pulley at one end of the chairlift came loose and part of the structure supporting it collapsed, causing a cable to lose tension and several seats to fall.

Dozens of people left hanging on the 15m-high (50ft) chairlift were helped down.

Jaime Pelegri, who was on the lift, told the BBC that a cable lost tension before the chairs on his side of the structure fell.

“It was very scary, but very fast,” he said – adding that ambulances and helicopters arrived at the scene within 15 minutes.

Previously in a post on X: “Luckily we are fine but there are injured people, we have seen several stretchers coming down.”

Images on social media appear to show one of the chairlift’s flywheels off its upright. The cause of the incident is not yet known.

Regional President Jorge Azcón and Spain’s Minister of the Interior Roberto Bermúdez de Castro went to the scene.

Azcón wrote on X: “All the necessary services of the [government] are working to assist the affected and injured people.”

PM Pedro Sánchez said he had spoken with Azcón to offer the “full support” of the government.

A telephone line has been set up for the families of those affected.

The Astún resort, which is popular with Spanish skiers, is located in the Aragon region of the Pyrenees mountains, near the border with France.