Heavy rain struck Hong Kong and vast areas of Guangdong province on Tuesday morning, forcing schools to close and disrupting people trying to get to work.

The Hong Kong Observatory canceled the amber rainstorm warning — the lowest level in the city’s three-tier system — at 10:20 am following three hours of heavy rainfall and intense gusts.

The alert was issued at 7:30 am, as an active southwesterly airstream brought severe thundery showers to the Pearl River Estuary region, said the weather forecaster.

Many parts of Hong Kong recorded around 30 millimeters of rainfall, with urban areas and the northern New Territories seeing up to 40 mm.

Gusts reaching 80 kilometers per hour were reported in Tai O at 9:20 am, prompting authorities to urge residents to take shelter.

Many cities in neighboring Guangdong province faced even more severe conditions. Zhuhai issued a red rainstorm alert — the highest level in the Chinese mainland’s four-tiered alert system — after recording over 100 mm of rain in just three hours, forcing a whole-day suspension of kindergartens, schools and universities citywide.

READ MORE: HKO issues amber rainstorm signal

Zhongshan also upgraded to a red alert following 190.5 mm of rainfall, suspending morning classes. Maoming similarly shut all its schools.

The National Meteorological Organization maintained the mildest blue rainstorm warning for Guangdong province and Guangxi Zhuang autonomous region, forecasting potential floods, while Shenzhen expanded its orange alert, expecting an additional 30-50 mm of rain.