
Over 130mm fell in three hours, far exceeding the city's "limited" drainage capacity, Construction Department spokesman Do Xuan Anh said.
Over 100mm fell in outskirt districts such as Dong Anh and Ha Dong Town. In the Long Bien area nearly 160mm fell.
About 22 key points in the city were under 30-40cm of flood water.
Many of them were flooded up to half a metre deep, particularly, the Kim Lien underpass, which connects Dai Co Viet and Dao Duy Anh streets in Hai Ba Trung District. It was flooded with up to 1.2m of water, the third time the tunnel has been flooded since it began operating in June last year.
The downpour caused traffic jams in many streets such as Le Duan, Kim Ma, Ba Trieu, Thai Ha and Nguyen Du.
"I tried many ways to find a path to my office but it seemed that every street was flooded, making it hard for vehicles to move," said IT company official Nguyen Thanh Huong, who works in Thai Ha Street .
"It took me two hours to go to my office instead of the normal half an hour," she said.
Wind blew down many trees which also affected traffic flows.
Two people in Hai Ba Trung District's Truong Dinh street and another person in Ba Dinh District's Ngoc Ha street died from electrocution when their houses were submerged.
The Ha Noi Electricity Company warned that wet walls increased the risk of electrocution during heavy rain.
He said the company had shut down hundreds of transformer stations in the city for safety reasons and cut 16 electricity lines of 22kV while workers check flooded areas.
More than 1,500 workers from the Ha Noi drainage company, in co-operation with police and city departments of transport and construction, were mobilised to dredge drains, remove rubbish and keep traffic order.
All 11 pumps of the Yen So pumping station were put into operation.
New drainage to be completed later this year is predicted to cope with more than 300m rain.
More rain was tipped for Ha Noi today and over the next few days, National Forecast Centre deputy director Le Thanh Hai said.
However, the falls were predicted to be less 100mm, he said.
The centre also warned heavy rain was predicted for the south of the city and throughout the region.
Storm in East Sea
A storm, named Conson, had formed in the East Sea and was moving in a west to north-west direction at a speed of 20-25kmph, the centre said.
At 1pm yesterday, the eye of the storm was at 14.4 degrees north latitude and 123.5 degrees east longitude, about 220km from south-east of the Luzon island of the Philippines, with the strongest wind up to 117kmph near its centre.
At 1pm tomorrow, the eye of the storm was forecast to be at 18.2 degrees north latitude and 114 degrees east longitude, 230km from the north-east of the Paracel Islands.
The National Steering Committee for Search and Rescue yesterday sent a message to branches in provinces and cities from Quang Ninh to Khanh Hoa and ministries of national defence, foreign affairs, public security and transport.
The message stated Conson would grow stronger tomorrow and cause danger to ships in the East Sea.
It called on coastal provinces and cities from Quang Ninh to Quang Ngai and relevant ministries and agencies to take measures to cope with Conson and instruct boat owners in Da Nang and Quang Ngai to leave dangerous areas in the north-east of the East Sea.
Owners of oil exploitation projects and water vehicles were required to take required safety measures and health departments were required to prepare medicines and regularly report to the Health Ministry's steering committee for disaster prevention and search and rescue.