A man killed himself with a bomb outside Brazil’s Supreme Court after trying to enter the building on Wednesday, officials said, stirring security concerns before the country hosts global leaders from the Group of 20 major economies.

The blasts come five days before the G20 heads of state meet in Rio de Janeiro, followed by a state visit to the capital Brasilia by Chinese President Xi Jinping.

The first of two explosions went off on Wednesday evening in a parking lot near the court building and a second blast came seconds later in front of the court, where the man’s body was found.

Federal District Vice Governor Celina Leao said preliminary information suggested the man had killed himself with explosives after trying to enter the Supreme Court. She said he owned a nearby car in which another explosion blew open the trunk.

Leao said she hoped it was the crime of a “lone wolf,” but she could not be sure. Police said they had not made a final identification of the dead man as they were confronting the risk of additional explosives on the body.

The explosions took place around the Plaza of the Three Powers, an iconic square in Brasilia connecting the principal buildings of Brazil’s three branches of federal government.

It was the scene of riots on Jan. 8 last year when supporters of former President Jair Bolsonaro ransacked the buildings to protest his electoral defeat.

Police deployed a bomb squad with an explosive disposal robot to the square in the heart of Brazilian capital to investigate the blasts.

The Supreme Court justices had just ended a plenary session when the blasts happened and were quickly evacuated safely, the court said in a statement.

President Luiz Inacio Lula da Silva had left the executive palace on Wednesday night shortly before the explosions.