MANILA » Emergency services and residents in the Philippine capital cleaned up and restored electricity today after a powerful typhoon unleashed floodwaters that killed at least 20 people and sent huge waves crashing over sea walls.

Most deaths occurred in and around metropolitan Manila, which already was soaked by heavy monsoon rain ahead of the arrival of Typhoon Nesat, which brought more downpours and wind gusts of up to 93 mph.

The typhoon blew out of the Philippines today packing winds of 75 mph and was expected to make landfall on China’s Hainan island on Thursday night or early Friday.

The Philippine disaster agency said 35 people were still unaccounted for and that 108 had been rescued.

Power supply was gradually restored to the downtown area, which was strewn with trash and fallen bamboo pieces washed ashore by storm surges. The Metro Rail Transit also resumed operations.

Some areas were still flooded, including Manila Ocean Park facing Manila Bay and a major thoroughfare, Taft Avenue. The nearby U.S. Embassy, which was inundated Tuesday, remained closed.

Manila Mayor Alfredo Lim said huge waves as high as coconut trees breached a 65-foot-long sea wall astride a popular promenade, allowing sea water from Manila Bay to rapidly engulf hotels, a hospital, business offices and several blocks of residential areas in waist-deep floodwaters.

"This is the first time that this kind of flooding happened here," Lim said.

Strong winds toppled about 40 huge trees around the capital’s tourist district, and 3,500 people were moved from shantytowns into three school buildings, where they spent the night huddled amid continuing rain.

Emergency repair crews were clearing roads of trees, debris and stalled cars as schools and offices reopened today.

The massive flooding came a day after this sprawling, coastal city of 12 million held two-year commemorations for the nearly 500 people killed during a 2009 cyclone, which dumped a month’s rainfall in just 12 hours. The geography of the archipelago makes it a welcome mat for about 20 storms and typhoons from the Pacific each year.

Some residents acted more quickly this time to evacuate homes as waters rose, including in the Manila suburb of Marikina, where 2,000 people escaped the swelling river by flocking to an elementary school, carrying pets, TV sets, bags of clothes and bottled water.