RIO DE JANEIRO >> The explosions that shook Brazil’s capital Wednesday evening and prompted an evacuation were an act of terrorism by a lone attacker who sought to violently disrupt democracy, police officials said Thursday.

Authorities said the only person killed was the attacker, and no one was injured. But the two explosions took place near the nation’s Supreme Court in Brasília, the capital, and put the nation on edge just days before the country is set to host a major Group of 20 summit, which President Joe Biden and other world leaders are expected to attend.

The attack echoed the violence that descended on Brasília after the election of President Luiz Inácio Lula da Silva nearly two years ago, fueling worries about renewed tensions after a period of relative calm. While tensions have subsided since, Brazil’s far right has appeared energized in the days since President-elect Donald Trump’s sweeping return to power in the United States.

Authorities identified the attacker as Francisco Wanderley Luiz, 59, a locksmith from the southern state of Santa Catarina. They said he had arrived in the capital several months earlier.

They described the act as a suicide bombing that involved “long-term planning” by an attacker who appeared to have acted alone, but they linked the attack to broader political extremism. Officials said it was too soon to say if Luiz had received funding or help from others.

“The investigation will reveal if there are other connections, if there are other networks, that are behind it,” said Andrei Passos Rodrigues, director general of the Federal Police, said at a news conference Thursday.

“We still don’t know the motive for the crime,” he said, adding that it is being treated as “a terrorist act.” He said the attack showed that “extremist groups are active” and highlighted the need for authorities to act swiftly.

Police said the attack appeared to target justices of Brazil’s Supreme Court.

Officials confirmed that Luiz, also known by his online nickname Tiu França, unsuccessfully ran for local office in 2020 with the conservative Liberal Party, currently associated with former President Jair Bolsonaro.

Brazilian Vice President Geraldo Alckmin called the explosion “sad and serious” and said the country is working continuously “to reduce this violence, these absurd acts that compromise peace, democracy and security.”

The blasts Wednesday occurred 20 seconds apart around 7:30 p.m., local officials said. The first explosion was in the trunk of a car in a parking lot near the Supreme Court. Seconds later, a second bomb detonated in a nearby plaza near Brazil’s Congress and the offices of Lula, who was not at his offices when the blasts occurred, officials said.

That explosion appeared to have killed the attacker, according to police, who said Thursday that they had also found a trailer nearby containing explosives.

Authorities said the bomber had tried and failed to enter the Supreme Court building before the explosions. Video surveillance showed he had circulated within the area before the bombs went off.