It's meant to be the city that never sleeps.

But with New York on coronavirus lockdown, the city stands empty, its neon advertising playing to no-one.

It comes as New York State's COVID-19 toll continues to rise at a devastating pace. There have been more than 4,000 deaths and 122,000 cases.

President Donald Trump said 1,000 military personnel, mostly doctors and nurses, would be deployed to New York City to "assist where they're needed the most".

Some 85,000 volunteers - including 22,000 from out of the state - have signed up to help in New York.

Hours earlier, New York City sent a wireless emergency alert to its 8.6 million residents urging licensed health workers to volunteer.

The mayor has estimated the city will need 45,000 more medical personnel to fight the pandemic through April and May.

The state is continuing its hunt for urgently needed ventilators, said New York governor Andrew Cuomo.

He thanked the Chinese government for donating 1,000 of the life-saving devices.

But only 2,500 ventilators from a separate order for 17,000 from China had arrived so far, he added.

Cuomo warned that infections in counties on the city-adjacent Long Island were like "fire spreading".

The densely populated area hosts 22 per cent of those hospitalised statewide, with cases growing steadily over the past 10 days and spreading away from the city.