There have been big crowds at beaches across the US as Americans enjoyed the Memorial Day weekend that marks the unofficial start of their summer.

The gatherings brought warnings from authorities as thousands flouted coronavirus social-distancing rules, and risking a resurgence of the scourge that has already killed nearly 100,000 Americans.

Sheriff’s deputies and beach patrols tried to make sure people kept their distance from others as they soaked up the rays on the sand and at parks and other recreation sites around the country.

In the Tampa area, along Florida’s Gulf Coast, the crowds were so big that authorities took the extraordinary step of closing car parks because they were full.

Dr Deborah Birx, co-ordinator of the White House coronavirus task force, said she was “very concerned” about scenes of people crowding together at the weekend.

“We really want to be clear all the time that social distancing is absolutely critical. And if you can’t social distance and you’re outside, you must wear a mask,” she said on ABC talk show This Week.

In Missouri, people packed bars and restaurants at the Lake of the Ozarks at the weekend. One video showed a crammed pool where holidaymakers lounged close together without masks, St Louis station KMOV-TV reported.

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In Daytona Beach, Florida, gunfire erupted on Saturday night along a beachside road where more than 200 people had gathered and were seen partying and dancing, despite the restrictions. Several people were wounded and taken to the hospital, authorities said.

Officials in California said most people were covering their faces and keeping their distance even as they ventured to beaches and parks. Many southern California beaches were open only for swimming, running and other activities. Sunbathing and group activities such as volleyball were prohibited.

The US is on track to surpass 100,000 coronavirus deaths in the next few days, while Europe has more than 169,000 dead, according to Johns Hopkins University. Worldwide, more than 5.3 million people have been infected and 342,000 have died.

The New York Times marked the horror by devoting Sunday’s entire front page to a long list of names of those who have died in the US. The headline: “An incalculable loss”.

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Meanwhile, President Donald Trump, who went golfing for the second day in a row after not playing for weeks, told Sinclair Television he was feeling fine after taking a two-week course of the unproven drug hydroxychloroquine, which can have deadly side effects, and a zinc supplement.

Mr Trump has spent weeks pushing the drug against the advice of many of his administration’s top medical professionals.

Donald Trump says he feels fine after taking controversial anti-malarial drug hyrdrychloroquine. Photo: AAP

The issue of wearing masks in public and staying apart has become fraught politically, with some Americans taking to the streets to protest such rules as a violation of their rights.

Republican Governor Mike DeWine of Ohio, who has been targeted by such demonstrations, insisted the precautions should not be a partisan issue.

“Its been very clear what the studies have shown, you wear the mask not to protect yourself so much as to protect others,” he told NBC’s Meet the Press.

On Sunday, the Trump administration announced it was adding Brazil to its travel ban list. The ban applies to foreign nationals who have been in Brazil in the 14 days before seeking travel to the US.

Across Europe, meanwhile, a mishmash of travel restrictions appears to be on the horizon, often depending on what passports visitors carry.

France is relaxing its border restrictions from Monday, allowing in migrant workers and family visitors from other European countries. Italy, which plans to open regional and international borders on June 3 to boost tourism, is only now allowing locals back to beaches in their own regions with restrictions.

Faithful socially distancing in St Peter’s square during Pope Francis’s blessing. Photo: AAP

In Vatican City, the faithful gathered in St Peter’s Square for the first time in months for the traditional Sunday papal blessing – but they kept their distance from one another.

In Paris, about 2000 Muslims gathered for Eid al-Fitr prayers at a sports complex, spaced a metre apart and wearing masks.

Beachside communities in England urged people to stay away after rules were eased to allow people to drive any distance for exercise or recreation. The city of Brighton said: “Wish you were here – but not just yet.”

-AAP