Protesters took to the streets in Milan, Turin and several other Italian cities on Monday in anger over the latest COVID-19 restrictions, which have shuttered cinemas, gyms and other leisure venues and have forced cafes and restaurants to close early.

The protests, at times, turned violent as some people smashed storefront windows, looted shops, set fires and hurled objects at police, who used tear gas to clear the tumultuous crowds.

A number of people were detained overnight in connection to the violence and vandalism in various cities and towns. More than two dozen people were reportedly arrested in Milan alone.

Italy, once the epicenter of the coronavirus pandemic, has seen an increase in infections in recent weeks. Over the weekend, the country's civil protection agency confirmed a record 21,273 new cases of COVID-19. As of Monday night, the cumulative total was 542,789 cases with 37,479 deaths.

ABC News' Clark Bentson and Phoebe Natanson contributed to this report.

Researchers have stopped testing a combination of remedesivir with one of Eli Lilly and Company's experimental antibody treatments in hospitalized COVID-19 patients, after an independent review of results found a "lack of clinical benefit."

The National Institute of Allergy and Infectious Diseases, which is funding the clinical trial, said in a statement Monday that it plans to test other experimental drugs as COVID-19 treatments in the study.

Eli Lilly and Company said that all other studies of its monoclonal antibody drug, bamlanivimab, will continue, including one in recently diagnosed COVID-19 patients with mild to moderate cases and another in people at risk of infection.

"While there was insufficient evidence that bamlanivimab improved clinical outcomes when added to other treatments in hospitalized patients with COVID-19, we remain confident based on data from Lilly’s BLAZE-1 study that bamlanivimab monotherapy may prevent progression of disease for those earlier in the course of COVID-19," Eli Lilly and Company said in a statement Monday.

Earlier this month, the Indianapolis-based pharmaceutical company asked the U.S. Food and Drug Administration to authorize emergency use of bamlanivimab in non-hospitalized individuals with mild to moderate cases of COVID-19.

Russia registered 320 more deaths from COVID-19 in the last 24 hours, setting a new national record, according to the country's coronavirus response headquarters.

The country's previous record of 317 deaths in a 24-hour reporting period was set less than a week ago.

An additional 16,550 new cases of COVID-19 were also confirmed in the past day, down from a peak of 17,347 the day prior, according to Russia's coronavirus response headquarters.

Moscow remains the epicenter of the country's outbreak and recent surge. More than 26% of the new cases -- 4,312 -- and over 19% of the new deaths -- 61 -- were reported in the capital.

The nationwide, cumulative total now stands at 1,547,774 cases with 26,589 deaths, according to Russia's coronavirus response headquarters.

After record increases in new infections and deaths, Russia’s health and consumer rights regulator, Rospotrebnadzor, issued a decree on Tuesday introducing a nationwide mask mandate and ordering all clubs, bars, restaurants and other entertainment venues to be closed between 11 p.m. and 6 a.m. Russian authorities have repeatedly said they will not impose another nationwide lockdown.

The Eastern European country of 145 million people has the fourth-highest tally of COVID-19 cases in the world, behind only the United States, India and Brazil, according to a real-time count kept by Johns Hopkins University.

ABC News' Alina Lobzina contributed to this report.

There were 66,784 new cases of COVID-19 identified in the United States on Monday, according to a real-time count kept by Johns Hopkins University.

The latest daily tally is nearly 6,000 more than the previous day but still less than the national record of 83,757 new cases set on Friday.

An additional 481 fatalities from COVID-19 were also registered nationwide Monday, almost half the previous day's count and down from a peak of 2,666 new deaths in mid-April.

A total of 8,704,524 people in the United States have been diagnosed with COVID-19 since the pandemic began, and at least 225,735 of them have died, according to Johns Hopkins. The cases include people from all 50 U.S. states, Washington, D.C. and other U.S. territories as well as repatriated citizens.

By May 20, all U.S. states had begun lifting stay-at-home orders and other restrictions put in place to curb the spread of the novel coronavirus. The day-to-day increase in the country's cases then hovered around 20,000 for a couple of weeks before shooting back up and crossing 80,000 for the first time on Oct. 23.