Typhoon Utor touched down in Hong Kong on Wednesday and is heading for China, according to the Associated Press.
With tens of thousands evacuated, Hong Kong's stock market was completely shut down in advance of the storm, which also managed to sink a cargo ship as it arrived, said the AP.
Utar is expected to be the strongest typhoon to hit China this year, according to China's state-run Xinhua news agency.
Over 158,000 people in China's southern provinces have fled in anticipation of the storm, Xinhua said.
Storms get very serious in the Pacific this time of year, Reuters reported, with cyclones common in the South China Sea as they pick up strength from warm waters and then dissipate over land.
At least one person in Hong Kong has been reported hurt in storm-related incidents. Utor left at least seven dead and several missing when it ravaged the Philippines earlier this week, Agence France-Presse said.
The government said four people had been confirmed killed, and 11 were missing after Utor, the strongest storm this year, swept across the north of the country on Monday.
"Trees have fallen down, roofs have been torn off houses, electric poles and electric towers have collapsed," civil defence office spokesman Reynaldo Balido said, describing chaos from coastal towns to mountain villages hundreds of kilometres apart.
According to Philippines' Manila Standard, officials estimate storm damage will cost more than 816.5 million pesos (over $18 million).