The Olympic Games Organizing Committee has opened an investigation in light of a violent incident Tuesday night in which a bus carrying journalists and volunteers between venues in Brazil had its windows shattered, according to multiple reports.

Mario Andrade, the Rio2016 spokesman, told the Guardian that three journalists suffered minor injuries and the cause remains unknown.

The bus was making its way from the Games basketball venue to the main Olympic Park at Barra da Tijuca when, according to passengers, two shots were heard hitting the vehicle. Windows shattered and flying glass left two people with minor lacerations.
“We don’t know yet if it was stones or bullets. The police are investigating,” Andrade said. Some reporters on the bus, which was traveling from Deodoro to the Olympic Park, reported hearing two gunshots.

There was no debate over the damage done to the bus, though.

The lead-up to the 2016 Olympics were beset with concerns about Rio’s ability to competently host the Games. While the athletes have been compelling, the atmosphere outside the arena has been inflamed at times.

On Saturday, a bullet flew through the media tent at the Olympic equestrian center and prompted an investigation by the organizing committee.