Protesters set fire to Australia’s Old Parliament House on Thursday, officials said, damaging the entrance to the historic building, as a group of demonstrators clashed with police and journalists in the capital, Canberra.

The circumstances surrounding the blaze were not fully clear, but protesters calling for improved treatment of Indigenous people had assembled outside the building. At the same time, a group named MMAMV Australia — for Millions March Against Mandatory Vaccinations — live-streamed the fire on Facebook, after posting from the building the previous day, vowing to return “until the job is done” and using the hashtag #takeoldparliament.

Other posts using the hashtag focused on Indigenous lore and colonial invasion and fighting a tyrannical empire.

The building, which was the seat of Australia’s federal Parliament between 1927 and 1988, is now a popular tourist attraction and houses the Museum of Australian Democracy.

“A police investigation into the cause of the fire has commenced,” a spokesperson said. “Old Parliament House will remain closed until further notice.”

The building was evacuated and the blaze was quickly extinguished by firefighters, police added.

Prime Minister Scott Morrison said authorities should act swiftly to ensure those responsible faced consequences.

“I am disgusted and appalled by behaviour that would see Australians come and set fire to such a symbol of democracy in this country,” he said in a news conference.

Earlier, Michael McCormack, a conservative lawmaker, said protesters were heard chanting “let it burn.”

“How disgraceful,” he wrote on Twitter. “An outrageous attack on our democracy, our history, our sovereignty.”

A spokesperson for the Aboriginal Tent Embassy, a protest camp that has occupied a site outside Old Parliament House for decades, did not immediately respond to a request for comment.

The MMAMV Facebook page shared a video of protesters clashing with police at the scene, while local journalist Rachel Baxter tweeted footage of protesters targeting media workers.

MMAMV has organized protests over the past six months in Sydney, Melbourne and other cities around the country, with speakers including far-right politician Pauline Hanson. Its Facebook page shares posts and images critical of vaccination and medications. It also posts about child trafficking concerns and freedom.

The group does not appear to be associated with Indigenous organizations or issues. At Thursday’s protest, however, some of those present waved the Indigenous flag, wore dot-painting shirts, carried Indigenous instruments and appeared to perform an Indigenous dance in front of the fire.

The building was also forced to close last week because of a fire during a protest, which was reported as an accident.