A man killed himself with a bomb outside Brazil’s Supreme Court after trying to enter the building on November 13, officials said, raising security concerns ahead of the country hosting world leaders from the Group of 20 major economies.

The explosions 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 the two explosions went off Wednesday night in a parking lot near the courthouse, and a second explosion came seconds later in front of the courthouse, where the man’s body was found.

Federal District Deputy Governor Celina Leao said preliminary information suggested the man had killed himself with explosives after trying to enter the Supreme Court. She said she owned a car nearby where another explosion blew out the trunk.

Leao said she hoped it was a “lone wolf” crime, but she couldn’t be sure. Police said they have not made a final identification of the dead man because they face the risk of additional explosives on the body.

The explosions took place around the Plaza de los Trei Powers, an iconic plaza in Brasilia that connects the main buildings of the three branches of Brazil’s federal government.

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

Police sent a bomb squad with an explosives disposal robot to the square in the heart of Brazil’s capital to investigate the explosions.

Supreme Court judges had just concluded a plenary session when the explosions occurred and were quickly evacuated to safety, the court said in a statement.

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