Military jets flew over US cities on Saturday to salute frontline workers in the country with the highest coronavirus caseload and death toll in the world.

Residents of the nation's capital Washington, as well as Baltimore and Atlanta were treated to sights of the Navy's Blue Angels and the Air Force's Thunderbirds arcing across the sky.

Crowds turned out on the National Mall to see the jets fly in formation past sites such as the US Capitol and the Washington Monument.

Most of those in attendance appeared to be following social distancing rules, and many wore face masks.

"Proud to see the #AmericaStrong salute to our healthcare & frontline workers with a spectacular flyover today in Washington, D.C. Thank you to the @AFThunderbirds and @BlueAngels for this beautiful display of solidarity," first lady Melania Trump tweeted, including a photo of herself watching the fly-by from outside the White House.

The Thunderbirds hailed health workers and first responders battling the novel coronavirus, which has infected more than 1.1 million in the US and killed more than 66,000.

"They are an inspiration for the entire country during these challenging times and it was an honor to fly for them today," the group said on Twitter.

The Blue Angels and Thunderbirds last month flew over US virus epicenter New York City, as well as Newark and Trenton, New Jersey and Philadelphia.