The victims were confirmed as residents of Sirah, Tawahi and Al-Areesh districts in the southern coastal city of Aden, a statement by Aden Governorate Security Department said.
At least 75 houses collapsed in the central Crater district, nearby Khormaksar, as well as Sheikh Othman and Tawahi, the statement added.
Video footage and images circulating on social media showed barrages of water sweeping through the streets, submerging cars and shopfronts underwater.
In one distressing video, a group of men are seen saving an elderly man who was swept away in his wheelchair.
The updated statistics came after Yemen's Prime Minister Maeen Abdulmalik Saeed appealed for urgent emergency assistance from allies and relief organisations to aid what he described as a "disaster" in Aden.
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Yemen's Saudi-based President Abedrabbo Mansour Hadi ordered civil defence and security forces to assist those affected by the flash flood, which left nearly all of the city immobilised and caused widespread power outages.
Similar scenes were witnessed last month when at least two people were killed in Yemen after severe flooding caused serious damage to the capital, just as authorities were rolling out prevention measures for the novel coronavirus.
A man and a woman were swept away by the flash floods in Aden. The pair were pulled from the water but died on their way to hospital, according to local newspaper Aden al-Ghad.
Over 75mm of rain fell in 24 hours, according to monitoring site Floodlist. At least five people were also injured, as the floods tore through streets, sweeping away cars, damaging homes and causing a power outage.
Experts expressed concern for Yemen, where cholera, dengue fever and now Covid-19 has spread. Stagnant water from the flooding could also lead to mosquitos that may carry infectious diseases.
The floods came just a day after UNICEF appealed on Monday for an additional $92.4 million to help fight the coronavirus pandemic in the Middle East and North Africa, with Yemen being a top concern, said Ted Chaiban, the regional chief of UNICEF.
After five years of civil war, half the health centres in Yemen no longer operate, while two million children are malnourished, including 400,000 who suffer from severe acute malnutrition.
"If you don't get support to them every month, you have a 50 percent increase in the mortality rate among those children (with severe malnutrition)," Chaiban told The Associated Press.
"It was already critical to address the needs of children in Yemen. With Covid-19, now you've got this extra layer of vulnerability."
An estimated 24 million Yemenis - more than 80 percent of the population - depend on some form of humanitarian or protection assistance for survival, according to the UN.
More than three million people are displaced, many in camps that are especially vulnerable to disease.
The country's health system, which has all but collapsed since the conflict broke out in 2014, is feared by many to be ill-equipped to handle the coronavirus crisis.
On Wednesday, reports confirmed Yemen will receive tens of thousands of coronavirus testing kits and medical equipment from a group of multinational companies to bolster its fight against coronavirus, in a project spearheaded by the International Initiative on Covid-19 in Yemen (IICY).
IICY said that its first 34-tonne shipment would reach the war-torn country next week, Reuters reported.
The shipment will include 49,000 virus collection kits, 20,000 rapid test kits, and five centrifuges, as well as equipment to enable 85,000 coronavirus tests and 24,000 Covid-19 nucleic acid test kits, Reuters reported.
IICY, which is part of the charity arm of multinational conglomerate Hayel Saeed Anam, Tetra Pak, Unilever, the World Bank-backed Yemen Private Sector Cluster, and the Federation of Yemen Chambers of Commerce and Industry, will work with the United Nations to distribute the equipment.
More than 200 ventilators and half a million masks will also be delivered.
Meanwhile, Yemen's war shows no signs of abating, almost two weeks after the Saudi-led military coalition declared a unilateral truce due to the coronavirus threat looming over the impoverished nation.
On Friday, Yemen's Emirati-backed separatist movement, the Southern Transitionary Council (STC), warned tensions with the Saudi-backed government are rising to the point where a war between the two sides is "imminent".
In a statement, the STC said it had informed the ambassadors of major countries to Yemen, as well at the UN envoy Martin Griffiths, that "the outbreak of war is imminent" after "violations by the government" that have prevented a "sustainable political agreement" between the two sides.
The STC accused the internationally-recognised government of attempting to regain control of southern governorates in violation of the ceasefire agreed in November.
Read also: Yemen in Focus: Escalating violence undermines ceasefire efforts
The southern governorate of Abyan has witnessed unprecedented escalations in recent days, after the separatists sent hundreds of troops to the area in what it says was to "strengthen its sovereignty" against the government.
The STC also accuses the government of trying to regain control over Aden, which was seized by the secessionists in August in a brutal battle.
The Riyadh Agreement power-sharing deal agreed in November was designed to unify Saudi-backed government and UAE-backed separatist forces, but since March, frequent clashes have signalled the agreement is faltering.
Another source of tension has been the geostrategic Socotra island, where UAE-backed militias have clashes with government forces.
The warning on Friday came as the UN's Yemen envoy Martin Griffiths maintained ceasefire negotiations between the government and the Houthi rebels are nearing completion, despite continuing military activities on several fronts.
"We are redoubling our efforts to bridge the outstanding differences between the parties," he said, adding that he feared fighting would continue on the ground until agreement was reached on the proposals.
The city of Marib, east of the capital of Sanaa, he added, "remains the centre of gravity of this war".
Yemen In Focus is a regular feature from The New Arab.
Sana Uqba is a journalist at The New Arab.
Follow her on Twitter: @Sanasiino