Heavy rain has flooded a gorge busy with hikers in the southern Italian region of Calabria, killing at least eight, the civil protection agency said.

At least another five are missing after the flash flood in the Raganello Gorge.

The prefect’s office said 23 people were rescued. They included a 10-year-old boy treated for hypothermia who was among seven the civil protection agency said were taken to hospital.

It is unclear how many people are missing but there were at least 36 hikers in two organised groups inside the seven-mile gorge, a popular aquatic trekking spot.

Rescuers work at the Raganello Gorge
Rescuers work at the Raganello Gorge (Francesco Capitaneo/Ansa/AP)

TV images showed rescuers scaling down the side of a steep rock face to take hikers to safety.

Guides are not required, making it impossible to know how many people were on their own in the canyon.

“The problem is we don’t know how many people were knocked over by this flood,” Carlo Tansi, the head of civil protection in Calabria, told Sky TG24.

“This is a split in the terrain that is very tight and high.”

At its narrowest point, it is just metres wide, with walls varying from 400 to 700 metres high.

Rescue vehicles gather in Civita
Rescue vehicles gather in Civita (Clemente Angotti/Ansa/AP)

Luca Franzese, of the alpine rescue squad in Calabria, said the flood water was 2.5 metres deep.

“The wave of flooding of the Raganello stream happens often in the winter, but it has never happened in the summer, when the stream is very popular among tourists,” he told the news agency Ansa.

The gorge on the eastern side of the Pollino National Park hosts aquatic trekking along the stream that cuts through the rock, where hikers pass by waterfalls and natural slipways.

The gorge is in three sections, the upper, mid and lower canyons, with hikes averaging between two and a half and three and a half hours and varying in difficulty.