Mr Bush's visit to Brazil has sparked angry protests.
This man is demonstrating against deforestation of the Amazon, which he fears will increase with a US-Brazil biofuels deal signed during the trip.
A heavy police presence has kept demonstrators away from Mr Bush.
The security operation involved helicopters flying over the president's hotel.
Meanwhile Mr Bush visited a bio-fuels facility with his Brazilian counterpart Luis Inacio Lula da Silva.
Thousands of people took part in a demonstration on Thursday, to mark Mr Bush's arrival.
Trouble broke out after a small group threw sticks and rocks at police, witnesses said.
Police fired tear gas and rubber bullets towards demonstrators.
They also used batons to subdue the protesters. Twenty people were injured, most of them police.