Massive moving cloud like ocean waves over Sidney

A spectacular shelf cloud was seen slowly moving over the ocean toward Sydney's Bondi Beach, before dumping rain on the city.

"Walking towards the beach it looked to me like a huge wave coming from the back of the ocean about to swamp us all!" Hannah Murphy told CNN on Friday.

"People were running from the streets to capture the unbelievable cloud formation."

 Mid-afternoon, the Australian Bureau of Meteorology issued a severe thunderstorm warning, urging residents to stay indoors and away from windows, unplug appliances and avoid using phones.