Supporters of former Brazilian president Jair Bolsonaro who refuse to believe he lost last year's election stormed the National Congress building and other government sites in the capital Brasília on Sunday.
They smashed the windows on the façade of the Congress building and stormed through the entrance hall, as shown on Brazilian television channels.
Hundreds of protesters had earlier advanced onto the grounds of the parliament, tearing down road blocks and pushing past police officers to finally reach the roof of the building.
Police used pepper spray and stun grenades but were unable to stop the rampage of the radical supporters of the former far-right leader. Some sat at the desks of parliament members.
"All vandals will be found and punished," left-wing President Luiz Inácio Lula da Silva, who has only been office for a week, said. "We will also find out who financed them."
By decree, Bolsonaro's successor ordered the federal government to take responsibility for public security in Brasília.
After the attack on Congress, Bolsonaro supporters moved to the Supreme Court. They broke windows there and entered the lobby, the news portal G1 reported. Later, they entered the Palácio do Planalto, the official workplace of the president, where they could be seen on television waving Brazilian flags running through hallways and offices.
The Supreme Court acted as a check on Bolsonaro's increasingly authoritarian rule during his four-year term and the judges were despised by his hardcore defenders.
Bolsonaro lost to Lula in the run-off election last October and left office at the turn of the year. He had never explicitly acknowledged his electoral defeat.
Radical Bolsonaro supporters had already protested repeatedly against Lula's victory after the election and called on the country's armed forces to stage a military coup.
Contrary to custom, Bolsonaro did not attend the inauguration of his successor Lula on New Year's Day and flew to the US with his family.
Lula was not in Brasília at the time of the attack. He had traveled to the city of Araraquara to get an update on the response to severe storms in the region.
"I condemn these anti-democratic acts, which must be urgently punished with the severity of the law," Senate President Rodrigo Pacheco wrote on Twitter.
"I spoke on the phone with the governor of the Federal District, Ibaneis Rocha, with whom I am in constant contact. The governor informed me that the entire police apparatus is focused on bringing the situation under control."
As blame began to be traded over the failure of law enforcement to prevent the pro-Bolsonaro riots, Rocha said on Twitter that the head of security for the capital, Anderson Torres, has been sacked.
"I have decided to dismiss the security minister of the Federal District and, at the same time, I have sent all the security forces to the streets to arrest and punish those responsible," Rocha wrote.
The head of Lula's ruling Workers' Party (PT) said Brasilia's governor was in part to blame for the attack.
"The government of the Federal District was irresponsible in the face of the invasion of Brasília and the National Congress," wrote Gleisi Hoffmann on Twitter "This was an announced crime against democracy, against the will of the voters and for other interests. The governor and his security minister, a supporter of Bolsonaro, are responsible for everything that is happening."
