A military officer next to the USNS Comfort Navy hospital ship located at Pier 90 to care for patients not related to Covic-19 on March 31, 2020 in New York City.

WASHINGTON — The captains of the U.S. Navy's two hospital ships said Thursday that the vessels have treated fewer than 20 patients since deploying to New York and Los Angeles in an effort to alleviate the pressure on local hospitals.

The USNS Mercy, the first of the twin hospital ships to deploy, arrived in Los Angeles last week and has since treated 15 patients.

"We're here in support of FEMA in the state of California so we're ready to answer whatever the demand signal is. And if that demand signal ramps up, we'll certainly be ready to accommodate that," U.S. Navy Capt. John Rotruck, the commanding officer of the USNS Mercy, told Pentagon reporters via telephone.

Rotruck added that Mercy's crew has yet to perform any surgeries onboard but has already treated a variety of injuries.

"People who have been in traumatic accidents who are now recovering, people with gastrointestinal and heart and lung problems. So pretty much the gamut of patients that you'd expect to see in a community hospital," he said.