BELGRADE, Serbia (AP) — Thousands of people protested the Serbian president's announcement that a lockdown will be reintroduced after the Balkan country reported its highest single-day death toll from the coronavirus Tuesday.

Police fired tear gas as the protesters, some chanting “Resignation! Resignation!" gathered in front of the downtown parliament building in Belgrade. Some briefly managed to enter the building by force, but were pushed back by riot police.

The protesters responded by hurling flares, stones, bottles and eggs at the police.

Earlier, President Aleksandar Vucic called the virus situation in the Serbian capital of Belgrade “alarming” and “critical” as the city's hospitals neared their capacity limits.

Vucic said the government would reimpose a curfew as of Friday. He said it will “probably" last from 6 p.m. on Friday till 5 a.m. on Monday. He also said the groups of no more than five people will be allowed together.

Many blame the autocratic Serbian president for lifting the previous lockdown measures just so he would cement his grip on power after parliamentary elections. He has denied those claims.

Soccer and tennis matches were played in packed stands and the election was held on June 21 despite warnings from experts that the mass gatherings without social distancing could lead to a new coronavirus wave.

The country’s Health Ministry said Tuesday that 13 people had died in 24 hours in Serbia and 299 new COVID-19 cases were confirmed.

That brought the total to 16,719 confirmed cases and 330 virus-related deaths since the start of the pandemic in Serbia, which went from having one of Europe’s strictest lockdowns to a near-complete reopening at the beginning of May.

On Tuesday, Montenegro introduced a compulsory quarantine for all people arriving from neighboring Serbia, citing coronaviorus health risks. Greece also banned Serb tourists from entering the country on Monday.

In an apparent tit-for-tat move, the Serbian government said Tuesday it was introducing a 14-day self-quarantine period for Montenegrin citizens who come to Serbia.

A country of 620,000, Montenegro split from the much larger Serbia in 2006, but many in Montenegro and Serbia remain opposed to the separation. Serbs represent about 30% of Montenegro’s population.

Montenegro, the first European country to declare itself free of the coronavirus, has recently seen an uptick in new confirmed cases.