The woman, in her 50s, was hiking with a male friend in his 40s in the mountains when they reached Dragon Ball Waterfall at around noon on Wednesday. But she slipped in the heavy rain and fell down a gully.

The man lost sight of her and could only recover her mobile phone. Police said they received a report at 12.39pm about the incident.

Police, firemen and Government Flying Service helicopters were deployed as Fire Services Department divers scoured the gully’s lower stream.

The accident happened nearly two hours after the observatory issued the second red rainstorm warning signal of the year at 10.45am.