Giant hailstones smashed windows of the large Festival Walk shopping mall in the Kowloon Tong area of Hong Kong on Sunday, flooding the facility. Metro stations at Kowloon Tong and Wong Tai also were flooded.

An online video showed a huge piece of debris crashing to the floor of the mall. Online pictures showed that some hailstones that fell on Hong Kong were the size of golf balls.

Hong Kong Observatory said that more than 70 millimeters of rain had fallen in some parts of the city in less than an hour, with 482 lightning strikes hitting Hong Kong Island and Kowloon.