Authorities in Berlin are investigating what appeared to be an arson attack early Sunday on Germany’s infectious disease institute leading the country’s response to the coronavirus pandemic.

Police said a security guard witnessed several individuals around 2:40 a.m. local time tossing bottle-based incendiary devices at the façade of the Robert Koch Institute (RKI), located in Berlin's Tempelhof neighborhood, German broadcaster Deutsche Welle reported.

Photos showed a shattered window partially blackened from flames at the building housing the federal government agency and research institute responsible for disease control and prevention. Police are investigating whether the attack was politically motivated, according to Reuters.

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A broken window is pictured at the Robert Koch Institute (RKI) for infectious disease in General-Pape-Strasse, as the coronavirus disease (COVID-19) outbreak continues, in Berlin, Germany, October 25, 2020. (Reuters/Annegret Hilse)

A broken window is pictured at the Robert Koch Institute (RKI) for infectious disease in General-Pape-Strasse, as the coronavirus disease (COVID-19) outbreak continues, in Berlin, Germany, October 25, 2020. (Reuters/Annegret Hilse)

Hours later, some 2,000 demonstrators gathered at Berlin's Alexanderplatz to protest new coronavirus restrictions enforced in the German capital as infection rates spiked nationwide in recent days. Police said most people in the crowd flouted social distancing and did not wear masks, according to Deutsche Welle

The protest was organized to coincide with the World Health Summit, which was to be held at a convention center in Berlin but was switched online to avoid contagion. German Health Minister Jens Spahn, as well as members of the Robert Koch Institute, which advises the government on public health restrictions, are set to speak at the three-day event.

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Germany – which has been widely praised for effectively slowing the spread of the virus at the onset of the pandemic – has seen spiking infection counts over the past few days.

RKI President Lothar Wieler said Thursday the daily number of confirmed cases hit 11,287, the first time Germany's 24-hour tally has been over the 10,000-mark since the beginning of the pandemic. He said the country's three-point strategy of “contain, protect, mitigate” to quickly track outbreaks, maintain hygiene and safety rules, and effectively treat infections needs the public's help to continue succeeding.

Germany's spring lockdown was much milder than those in many other European countries. It has reopened schools across the country, as well as shops, restaurants, and other businesses, albeit with mask regulations in some places, limits on how many people can gather in one place, and other precautions.

But German states have begun implementing stricter rules in recent weeks, as the numbers have again been rising.

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Though most Germans supported lockdown measures earlier this year, a new economic survey published last week showed the country’s consumers are growing increasingly pessimistic about the future amid growing fears of new restrictions.

Germany has seen at least 443,139 positive COVID-19 cases and more than 10,000 deaths -- making it the fifth European country with the most infections.

The Associated Press contributed to this report.