Spain also reported 812 new deaths, raising its overall confirmed death toll to 7,340.
Experts say those figures and ones in every other country are much lower than the actual impact of the pandemic, due to limited testing, counting irregularities and mild cases that have been missed.
Spain and Italy make up more than half the world's death toll of over 34,800 people from the virus that has upended the lives of billions and devastated world economies.
Their health systems have been crumbling over the weight of caring for so many desperately ill patients at once. Italy has by far the most reported virus deaths, at nearly 11,000.
At least six of Spain's 17 regions were at their limit of ICU beds and three more were close to it, authorities said Monday. Crews of workers were frantically building more field hospitals.
Despite the declining infection rate, Spanish health official Dr Maria Jos Sierra said there's no end to the stay-at-home restrictions yet in sight.
"Reducing the pressure on the ICUs will be important for considering de-escalation measures," said Sierra, who took over Monday as the health emergency center's spokesperson after its director tested positive.
Nearly 15 per cent of all those infected in Spain, almost 13,000 people, are health care workers, hurting hospitals' efforts to help the tsunami of people gasping for breath.
In hard-hit Madrid, flags were hoisted at half staff for an official mourning period. During a minute of silence for the dead, Madrid's Puerta del Sol central square was empty as bells tolled.
In a situation unimaginable only a month ago, Italian officials were cheered when they reported only 756 deaths in one day.
Italy has 97,689 confirmed infections but said the number of positive cases in the last day increased just 5.4 per cent and the number of deaths have dropped about 10 per cent a day since Friday.
''We are saving lives by staying at home, by maintaining social distance, by traveling less and by closing schools," Dr Luca Richeldi, a lung specialist, told reporters.
In a stark reversal of his previous stance, Trump extended federal guidelines recommending that Americans stay home for another 30 days until the end of April to slow the spread of the virus.
The turnabout came after Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said up to 200,000 Americans could die and millions become infected if lockdowns and social distancing did not continue.
"We want to make sure that we don't prematurely think we're doing so great," Fauci said.
The US now has more than 143,000 infections and 2,500 deaths, according to Johns Hopkins University, while around the world more than 735,000 people are infected.
Moscow went on its own lockdown Monday as all of Russia braced for sweeping nationwide restrictions.
The Russian capital of 13 million accounts for more than 1,200 of the country's 1,836 coronavirus cases.
"The extremely negative turn of events we are seeing in the largest European and US cities causes extreme concern about the life and health of our citizens," Moscow Mayor Sergei Sobyanin said.
Experts say the critical situations seen in hospitals in Italy and Spain will be soon heading toward the United States.
Coronavirus patient Andrea Napoli, 33, told The Associated Press he didn't remotely expect that he would be hospitalised, struggling for his life, since he was young and fit. But what he saw shocked him.
While he was being treated in Rome, three patients died in his ward.
He saw doctors stressed and exhausted from the long hours, out of breath from pushing equipment around, dressed in protective masks, suits and gloves.
''What I saw was a lot, a lot of pain. It was very hard,'' Napoli said.
"I heard screams from the other rooms, constant coughing from the other rooms."
For most people, the coronavirus causes mild or moderate symptoms, such as fever and cough. But for others, especially older adults and people with existing health problems, the virus can cause severe symptoms like pneumonia and be fatal.
More than 156,000 people have recovered, according to Johns Hopkins.
China's National Health Commission on Monday reported 31 new COVID-19 cases, among them just one domestic infection.
At the peak of China's restrictions, some 700 million people were ordered to stay home, but those rules are easing.
New York state remained the epicenter of the US outbreak, with the vast majority of the deaths in New York City.
But infections were spiking not only in cities but in Midwestern towns and Rocky Mountain ski havens.
West Virginia reported its first death, leaving only two states Hawaii and Wyoming with none linked to COVID-19.