Typhoon Ragasa has made landfall in southern China, where nearly two million people have been evacuated in preparation for its arrival.

It comes after authorities said at least 17 people had been killed and more missing in Taiwan after a lake burst on Tuesday, causing severe flooding in the island's east.

Ragasa was downgraded from a super to a severe typhoon on Wednesdaybut it remains highly destructive, with top winds of 241km/h (150mph) recorded in Taishan county in China's south-eastern Guangdong province.

The equivalent of a Category 5 hurricane, Ragasa is the world's strongest storm this year and has been roaring over the South China Sea for days.

Ahead of making landfall, 90 people were injured in Hong Kong as the storm skirted its coastline, the hospital authority said.

The typhoon made landfall on the coast of Hailing Island, Yanjiang City in Guangdong at about 17:00 local time (9:00 GMT) on Wednesday, according to Chinese state media.

It crossed the mainland with sustained winds of 144km/h and higher gusts. Wind speeds are expected to gradually weaken as the storm moves westwards over land but rain will be torrential and slow-moving across the region for several more days.

The southern Chinese cities of Zhuhai, Shenzhen and Guangzhou - all located in Guangdong - were braced for seawater intrusion from about midday local time.

In Zhuhai, police patrolled the streets with sirens and megaphones, telling people to stay at home.

Red alerts for landslides were also issued in the mountainous regions of Guangdong province.

Away from the Chinese mainland, authorities in Taiwan are still dealing with the destruction caused by Ragasa, which officials have described as being "far worse than anticipated".

Premier Cho Jung-Tai has demanded an inquiry into how evacuations were carried out after at least 17 people died after a barrier lake, formed by a landslide in July, burst its banks in Hualien county, causing severe flooding in the town of Guangfu. Others remain missing, the fire department said.

"We must investigate why evacuation orders were not carried out in the areas we had asked for, which led to such a tragedy," Cho told reporters. "This is not about assigning blame, but about uncovering the truth."

Earlier on Wednesday, the village chief of the township of Dama in Taiwan, home to about 1,000 people, said the entire village had been flooded and many people were still stranded as a result of the Matai'an Creek barrier lake burst.

"It's chaotic now," Wang Tse-an told Reuters news agency. "There are mud and rocks everywhere. Some flooding has subsided but some remains."

Some geologists have described the breach as a "tsunami from the mountains", as an estimated 15.4 million tonnes of water – equivalent to 6,000 Olympic-sized swimming pools – were released when the dam burst.

The flooding washed away several key bridges, submerged vehicles and left the ground floors of homes underwater. Many residents were trapped on upper storeys awaiting rescue.

Although floodwaters have receded in the city, thick mud and debris remain, and search teams continue to go door-to-door in hopes of locating the missing.

"I'm still in shock. I just can't imagine how this could have happened. This is one of the busiest areas in Hualien and the streets are lined with shops. We go to these places all the time but everything was destroyed yesterday," 42-year-old Awa, who runs a book shop with her husband in Guangfu Township, told the BBC.

The couple spent the night at an evacuation centre. Hualien is home to many indigenous tribes, and the couple belongs to the Amis community.

The government has established a front-line disaster response centre in Hualien, and the Ministry of National Defence has deployed troops to assist with rescue efforts.

Typhoon Ragasa has also caused disruption in Hong Kong and the Philippines.

Though the typhoon did not make landfall in Hong Kong, the hospital authority said 90 people were injured after it skirted the coastline, unleashing powerful winds and heavy rain.

The Hong Kong Observatory issued a level 10 warning for the storm on Wednesday - the highest it can issue - and urged people to stay inside.

Flights were grounded, and schools and some businesses shut. Flights were expected to resume at midnight on Thursday, the airport authority said.

Earlier in the week, Ragasa ripped through the Philippines' remote northern islands, leaving towns flooded, thousands displaced and at least eight killed.

Packing winds of 260kph (162 mph) at its peak on Monday, Ragasa is believed to be the most powerful storm the world has seen this year.

The China Meteorological Administration has described Ragasa as the "King of Storms".

It is expected to be more destructive than the other typhoons that made landfall in China's Guangdong province earlier this year.