Satellite images show the extent of destruction in the Libyan port city of Derna after heavy waters washed away bridges, streets and entire communities, leaving thousands dead and missing.

The heavy rain brought by Storm Daniel this weekend led to the collapse of two dams on the Wadi Derna River, which runs through the city and usually has a very low flow. The streams of water and debris left a trail of destruction.

A series of bridges crossed the Wadi, connecting a port area with the western part of the city.

The water – described by one official as “a tsunami” – swept away bridges, as well as entire blocks of residential buildings (including multi-storey complexes), government buildings and a large mosque.

In Al-Eilwa district, flooding was reported in 96% of houses.

Many of the properties that were built near the river have disappeared, leaving only the foundations of the buildings visible.

A coastal road near the port fell into the sea.

The city of Derna had 200,000 inhabitants before the storm.

The city’s mayor said that given the number of neighborhoods completely destroyed, between 18,000 and 20,000 people could have been killed.

Thousands of others are injured or missing, with many left without a place to live.

A United Nations analysis found that more than 2,200 structures were exposed to the water and at least six bridges and the port area suffered serious damage.

Hard-hit neighborhoods such as Al-Bilad and Al-Maghar on both sides of the river also had health centers used by people in the city, according to Reach disaster analysts.

Houses built on the dry riverbed on the sea side of the dam took the brunt of the water’s impact.

Hamad Shalawi, a member of the local disaster committee, said the town was destroyed within seconds and entire families had been killed.

“The geography of the city changed completely when half of the city fell into the sea,” he told the BBC’s Arabic service. (JO)