A bus carrying Rio Olympics journalists came under attack and police were investigating whether bullets were fired from the notorious City of God favela.
Rio 2016 organizers said two journalists suffered slight injuries in Tuesday's attack, which set off a new Olympic jitters four days after a bullet hit a Games media center.
Journalists in the bus hurled themselves to the floor after two windows were blown out. The driver put his foot down and got the passengers to the Games' main press center, France24 reported.
Rio 2016 said in a statement that police and army patrols had been stepped up but gave few indications on the cause. Rio is notorious for gun crime and gang violence.
The bus was returning from the Deodoro Olympic zone to the main press center and was passing near the City of God slum district when it was hit.
"Two impacts on the right side of the bus shattered two windows. A reporter from Belarus suffered a cut hand. There is confusion as to whether it was bullets or stones," Gaston Sainz of the Argentinian daily La Nacion, who was on the bus, told AFP.
"We threw ourselves to the floor and two kilometers later the police came and escorted us to the main press center with the broken windows," Sainz said.
On arriving at the media center, two passengers had minor injuries caused by broken glass cuts, the organizer's statement said.
The driver was to give a statement, while the bus was being examined by police.
Earlier, security forces conducted a controlled explosion near the finish line of the men's cycle road race.
Another suspect package was blown up on Tuesday near the luxury beachfront Copacabana Palace hotel.
