A helicopter rescued residents stranded during Typhoon Ragasa.

Aerial footage shows air crew in safety gear and helmets airlifting locals from their rooftops in the middle of a flooded residential area in Guangfu Township, Hualien County, Taiwan.

A woman and six men had been trapped in their homes when a nearby lake overflowed on September 23.

Local media reported that the Mataian landslide dam in the county overflowed at around 2:50 pm local time, sending torrents rushing downstream.

Super Typhoon Ragasa, described as the strongest storm of the year so far, has wreaked havoc across East Asia after tearing through the northern tip of the Philippines and Hong Kong, killing at least 10 people in the Philippines and displacing thousands. Taiwan has also reported 17 fatalities linked to the storm.

It made landfall in the Philippines' remote and poverty-stricken Babuyan Islands at 3 pm local time on Monday. It arrived as the country continues to grapple with weeks of severe flooding brought on by an unusually intense monsoon season.

Taiwan's state weather service forecasted 'extremely torrential rain' as Ragasa churns toward Taiwan.

The agency said: 'Its storm radius is quite large, about 320 kilometres (200 miles). Although the typhoon's centre is still some distance away, its wide, strong wind field and outer circulation are already affecting parts of Taiwan.'

The Central News Agency said at least six people were injured and more than 7,000 people were evacuated when the typhoon lashed the southern part of Taiwan.