0341 GMT February 17, 2019
Nearly half a million people had been evacuated from seven cities in Guangdong province of China, and the Hong Kong Observatory warned people to stay away from the Victoria Harbor landmark, where storm surges battered the waterfront reinforced with sandbags, aljazeera.com reported.
Mangkhut made landfall in Guangdong on Sunday.
The national meteorological center said southern China "will face a severe test caused by wind and rain" and urged officials to prepare for possible disasters.
On Sunday morning, the typhoon packed sustained winds of 155 kilometers an hour and gusts of up to 190 km/h.
The Hong Kong Observatory said although Mangkhut had weakened slightly, its extensive, intense rainbands were bringing heavy downfall and frequent squalls.
Hundreds of flights were canceled. All high-speed and some normal rail services in Guangdong and Hainan provinces were also halted on Sunday, the China Railway Guangzhou Group Co. said.
Footage posted on social media showed fierce winds throwing people to the ground, swaying buildings, smashed windows and serious flooding.
A video reportedly filmed in Hong Kong's Kowloon area showed scaffolding collapsing at a building site.