The Festival Walk shopping mall came under fire yesterday, accused of poor maintenance and a slow response to Sunday's flood following a burst pipe, as shopkeepers mopped up and counted the cost.
The criticism came as the Observatory warned that heavy rain and squally thunderstorms would continue to affect Hong Kong and the region for several days.
By 5pm yesterday, 54 flights had been cancelled and 433 flights delayed by the weather.
Sunday marked the earliest time in a year a red or black rainstorm warning has been issued.
Watch: Hailstorm hits Hong Kong
It emerged yesterday that two of six people killed by a landslide in Gaoyao, western Guangdong province, on Sunday afternoon were from Hong Kong, including a well-known fung shui master. They were among at least 16 to die as storms swept southern China.
Seven people in Hong Kong were admitted to hospital during the two hours of the black rainstorm.
Kowloon Tong was hit particularly hard.
The Buildings Department yesterday denied speculation that the flooding of Festival Walk was caused by hailstones breaking a glass panel. It said a broken rainwater pipe was to blame for water pouring into the centre.
About 10 shops and restaurants near the unwelcome waterfall were closed or partially shut to clean up the mess.
"It was not because the glass ceiling or glass windows were broken," a spokesman said.
A manager at the Cole Haan boutique said: "Someone was suddenly screaming outside on Sunday night, so I went out and had a look.
"It was like it was raining inside the mall. I then found water dripping from the ceiling of my shop."
Chan Chi-ming, head of the Hong Kong Institute of Vocational Education's department of construction, said he believed the pipe broke because of poor maintenance of connecting joints. After inspecting the mall, he said the managers of the shopping centre should have done more to protect customers.
"The mall should have immediately evacuated the shoppers because it was dangerous," he added.
Mapletree Greater China Commercial Trust, which bought the mall from Swire Pacific in 2011, said it would take more precautions to ensure the safety of tenants and visitors. Mapletree is owned by Singapore state investment firm Temasek Holdings.
Guangdong was among the worst-hit provinces as storms swept across southern China.
It suffered severe flooding, hailstorms and landslides and seven of the 16 deaths. Two people in the province were still missing. At Gaoyao, the six deaths included Hong Kong fung shui master Cheng Kwok-keung, who was working with another Hongkonger for a mainland client at a graveyard when a landslide hit.
Two farms, in Conghua district and Jiangmen city, that supply vegetables to Hong Kong said the storms had damaged 20 per cent of their crops.