As many as 2,000 people may have been drowned after a powerful storm unleashed catastrophic floods in the eastern Libyan city of Derna, according to the head of one of the country’s two rival governments. Ossama Hamad, prime minister of the eastern-based government, said on Monday that thousands were believed missing after torrential rains over the weekend. The Red Crescent in Benghazi had put the death toll closer to just 250, but the worst-hit area of Derna remained largely cut off with local leaders claiming the situation in the city was “out of control and a catastrophe”. A spokesperson for the Libyan army in the east, Major General Ahmed Al-Mismari, suggested that as many as 5,000 to 6,000 were missing in Derna, which has a population of 100,000. The precise number dead is hard to gauge with communications down and administration hampered by a decade-long battle for power between two rival governments each backed by their own militias. Aid agencies and wealthy Gulf states such as the United Arab Emirates were rushing emergency aid to the region, with local officials saying they needed stretchers, food and water. The deaths occurred after a powerful storm and heavy floods led to the collapse of two ageing dams, which released a swollen fast-moving river that simply washed away at least one neighbourhood. It is not known how many people were sleeping in the flats when the flood arrived. Residents first knew the dams had collapsed under the weight of the water when they heard an explosion in the middle of the night. One resident on social media said: “After sunrise we went out to the streets of Derna, but the streets were not there.” A Derna resident, Ahmed Mohamed, said: “We were asleep and when we woke up we found water besieging the house. We are inside and trying to get out.” The Derna municipal council announced on their official Facebook page that “the situation is catastrophic and out of control”. It called for international intervention and the opening of a sea corridor due to the collapse of most of the city’s roads. Kais Fhakeri of the Red Crescent said: “We recorded at least 150 deaths after the collapse of buildings. We expect the death toll to rise to 250. The situation is very catastrophic.” Heavy floods washed away vehicles, footage broadcast by eastern Libya’s Almostakbal TV showed. The channel also posted pictures of a collapsed road between Sousse and Shahat, home to the Unesco-listed archaeological site Cyrene.. Libya’s eastern-based parliament declared three days of mourning. Abdulhamid al-Dbeibah, the rival UN recognised Libyan prime minister based in Tripoli in Libya’s west, also announced three days of mourning in all the affected cities, calling them “disaster areas”. Dbeibah’s government is recognised by the Central Bank of Libya, which disburses funds to government departments across the country. Four oil ports – Ras Lanuf, Zueitina, Brega and Es Sidra – were closed from Saturday evening. The storm struck eastern Libya on Sunday afternoon, hitting especially the coastal town of Jabal al-Akhdar but also Benghazi, where a curfew was declared and schools were closed for several days.