Two explosions took place near Brazil’s Supreme Court on Wednesday night, prompting an evacuation of the area and killing one person, who the police said was believed to be the attacker.

The authorities identified the person killed as Francisco Wanderley Luiz, 59. A person with that name ran unsuccessfully for local office in 2020 under the banner of former President Jair Bolsonaro’s conservative Liberal Party.

The blasts in Brasília, the capital, happened 20 seconds apart at about 7:30 p.m., Celina Leão, the vice governor of Brazil’s Federal District, said at a news conference. The first occurred in the trunk of a car in a parking lot near the Supreme Court; the second was in a nearby plaza, which is also close to Brazil’s Congress and to the offices of President Luiz Inácio Lula da Silva, who narrowly defeated Mr. Bolsonaro in the 2022 election.

Officials said Mr. Lula was not at his offices when the blasts occurred.

Ms. Leão said the authorities were treating the incident as the work of a lone bomber, though their investigation was still underway. She said the person who was killed had tried and failed to enter the Supreme Court building before the explosions.

Images from the scene in news reports and on social media showed one body in the plaza, which is known as Three Powers Square. The authorities said they had not yet moved the body out of concern that unexploded devices might be attached to it. Military police officers and bomb squads were sweeping the area.

The car that blew up in the first explosion was registered to Mr. Luiz, who was from the southern state of Santa Catarina, according to the police.

A man with the same name ran unsuccessfully for city council in Rio do Sul, a town in Santa Catarina, as a Liberal Party candidate in 2020, receiving less than 1 percent of the vote. Local news reports on Wednesday said a post left on that person’s Facebook account before the explosions had threatened political figures and told police they had 72 hours to defuse a bomb.

“The Federal Police will investigate the explosions in the perimeter of the Three Powers Square with rigor and speed,” Brazil’s solicitor general, Jorge Messias, said in a post on X on Wednesday night. “We need to know the motive for the attacks, as well as restore peace and security as quickly as possible.”

In December 2022, a man tried to detonate a bomb near the airport in Brasília to protest Mr. Lula’s victory in the presidential election. The following month, supporters of Mr. Bolsonaro stormed and vandalized the Congress, the Supreme Court and the presidential offices, in an attack that echoed the Jan. 6, 2021, attack on the U.S. Capitol in Washington.