At least 11 people were killed in southern Italy when heavy rain flooded a deep mountain gorge filled with hikers, officials said.

The civil protection department said 23 people were rescued and about a dozen were hospitalised after surviving the flash flood of water in the Calabria region.

The 11th victim died in hospital.

At least five people were still missing, but the total could be higher because not all had entered the Raganello Gorge with official guides and registered.

Rescue squads worked through the night with spotlights, and helicopters took off at first light to survey the area.

Rescuers and citizens wait in the central square of Civita as rescue squads worked through the night with spotlights (KONTROLAB/AFP/Getty Images)

The nationalities of the dead and injured were not immediately known. Six of the victims were women and five were men. Most tourists and trekkers who visit the area, in the country’s deep south, are Italian.

In some places the Raganello Gorge, part of the Pollino National Park, is at the bottom of a narrow, 1km-deep gorge in the mountain.

TV footage showed rescue workers using ropes to scale the sides of the mountain to bring hikers to safety.

At least five were missing, but the total could be higher (KONTROLAB/AFP/Getty Images)

“This gorge filled up with water in a really short space of time and these people were catapulted out like bullets,” said Carlo Tansi, head of the civil protection department in Calabria.

“They ended up some 3km down the valley.”

Mr Tansi said the gorge was only about 4m (13ft) wide in some places, increasing the speed of the water and making the rescue more difficult.

“It is really difficult terrain, filled with obstacles because of the [geological] formation of the area,” said Eugenio Facciolla, the chief prosecutor of the provincial capital, Cosenza.

He said rescuers working under spotlights were trying to locate areas where some people may have survived by ending up on small patches of shore or tiny islands in the creek.

Rescuers were trying to locate areas where some people might have survived (KONTROLAB/AFP/Getty Images)

Helmeted mountain rescue squads rushed from the nearest town of Civita to reach the gorge, a popular tourist attraction in summer.

The most seriously injured were taken by helicopter to hospitals in Cosenza and Castrovillari.