People gathered at the site of a collapsed bridge in Nabeul following deadly flash flooding in the town of Bir Challouf. Image Credit: AFP

Tunisia - Flash floods in Tunisia's Cap Bon peninsula have killed at least five people, authorities said Sunday, as surging waters caused by heavy rains carried away homes, cars and chunks of road.

Saturday's storm caused water levels in some areas to rise as much as 1.7 metres, as bridges and roads were damaged in record rains that dropped the equivalent of nearly six months of average precipitation.

In most places, water levels had begun falling quickly, the interior ministry said, adding however that the death toll had risen to five after a teenager was electrocuted Sunday in Bou Argoub, 45 kilometres southeast of Algiers.

Two sisters were swept away as they left work at a factory in Bou Argoub, the ministry said.

"They were trying to cross rising wadi waters to get back home," Amir, a resident of the area, told AFP.

Wadis are river beds that are usually dry but are meant to carry away seasonal rains.

'Blocked' Wadis exacerbate floods

"The wadis have been abandoned for decades - there is no maintenance", he said, adding that the river beds are filled with trees, garbage and rubble.

A man in another area agreed that blocked wadis had exacerbated the flooding.

"It was raining since noon and it became torrential", said Moncef Barouni, a resident of the coastal town of Nabeul.

People gathering at the site of collapsed bridge following deadly flash flooding in the town of Bir Challouf. AFP

"The wadi in front of our house was blocked by trees and the water flooded over the bridge and onto the road," he told AFP.

In just minutes, "the water swept away the fence, then the boiler room, the summer kitchen and a part of the house," he said.

"I was scared for my life."

The storm dumped 200 millimeters of rain on Nabeul and up to 225 millimeters in the city of Beni Khalled, in the peninsula's centre, according to Tunisia's National Institute of Meteorology.

A man digging through the debris of his home following deadly flash flooding in the town of Bir Challouf. AFP

It was the heaviest rainfall since the institute began keeping records in 1995, it said, adding that it had issued a warning about the storms on Friday.

People angry about the situation demonstrated in Cape Bon, with Prime Minister Chahed calling for calm as excavators and pumps were put into action.

Videos posted to social networks showed surging waters carrying cars and chunks of road in the north of the peninsula.

Tunisian authorities said they had dispatched police, army and rescue teams to the region on Saturday afternoon, in addition to mobilising ambulances and two helicopters.

Chahed visited affected areas to meet survivors, as authorities took preventative measures in the Sahel region further south in case of further rains.

"The main thing today is to reopen roads and help those affected. There are regions that are still isolated," he said, quoted by private radio station Mosaique FM.

People cleaning the debris of the street following deadly flash flooding in the town of Dar Chaabane. AFP

The sun was out Sunday and receding water levels meant most of the area's roads were passable by car, the interior ministry's Zaag said, although the region's telephone networks were still largely out of service.

Traders surveyed damage to their shops and goods, while some schools said lessons would not take place on Monday.