More than 40 million Californians have been ordered to stay in their homes after the state's Governor predicted that more than half of them would contract coronavirus.

Key points: California has more than 1,000 cases of coronavirus and at least 18 people there have died during the outbreak

California has more than 1,000 cases of coronavirus and at least 18 people there have died during the outbreak About 56 per cent of people in the state are expected to become infected in the coming months

About 56 per cent of people in the state are expected to become infected in the coming months The Governor of California has asked Donald Trump to send a Navy hospital ship to LA to help

Issuing a state-wide lockdown order for all residents, Governor Gavin Newsom asked US President Donald Trump to send a US Navy hospital ship to the port of Los Angeles immediately.

He said experts were projecting that roughly 56 per cent of Californians, or about 25.5 million people, were expected to contract the respiratory illness over the next eight weeks.

"This is a moment we need to make tough decisions," Mr Newsom said.

"We need to recognise reality."

Mr Newsom said Los Angeles, which has a population of more than 12 million people, was likely to be "disproportionately impacted" by the pandemic in the coming weeks.

Just minutes before Mr Newsom announced the state-wide measures, LA Mayor Eric Garcetti said all indoor shopping malls, playgrounds and other gathering places would close at least until the end of the month.

Popular tourist spots like Hollywood Boulevard have been deserted. ( AP: David Crane/The Orange County Register )

"We're taking this urgent action to limit the spread of COVID-19 and save lives," Mr Garcetti said.

The new orders are stricter than the "shelter in place" directives given in more than a dozen Northern California counties already.

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California has been among the hardest hit states in the outbreak of COVID-19, with more than 1,000 confirmed cases and at least 18 deaths.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 5 minutes 43 seconds 5 m Dr Norman Swan answers some of your questions about the coronavirus outbreak ( Norman Swan )

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