The USNS Mercy, which docked in the Port of Los Angeles, will quickly become the city's largest hospital with 1,000 beds.

It will not receive coronavirus patients, but will instead take patients with a wide range of other conditions or injuries, in order to free up facilities on land.

The ship will help "ease the burden on our emergency rooms and ICUs when the cases of Covid-19 grow in the weeks ahead," tweeted Mayor Eric Garcetti on Friday.

It "will free up valuable beds that today are 80 percent or 90 percent filled already, to be able to deal with the onslaught of the COVID-19 patients that we see," Garcetti said in an earlier briefing on Thursday.

The 894-foot (272-meter) USNS Mercy hospital ship, a converted oil tanker, has 15 patient wards and blood bank capacity of 5,000 units.

California officials lobbied intensely for the ship to come to Los Angeles, overriding a competing claim from northwestern Washington state which is also badly affected but less populous.

California's latest official statistics show over 3,000 confirmed cases of coronavirus, with 65 deaths.

The Mercy's arrival precedes the passage of its sister ship, the Comfort, to New York -- now the US epicenter of the pandemic.

Los Angeles alone reported nine new deaths and over 400 new cases on Thursday.

"Disturbingly, we see that if this rate of increase continues in six days we will be where New York is today," said Garcetti.