Forecaster issues highest-level storm warning at 5.50am, prompting authorities to suspend all morning and whole-day schools.

Hong Kong came to a standstill on Tuesday as torrential rain pounded the city for the second time in less than six hours, triggering a rare black rainstorm warning, paralysing public services and flooding key urban districts.

Blackened skies unleashed record-breaking rains on Hong Kong and the high-tech cities surrounding South China's Pearl River Delta on Tuesday (Aug 5), disrupting hospitals and shuttering schools and law courts across the Asian financial hub.