Riots in the Ugandan capital Kampala have left at least one person dead and 64 wounded, according to the Red Cross.
It was the first time Uganda's growing protest movement had reached the capital.
Rioters burned tires in city centre streets as security forces fired tear gas and guns.
It was not clear if the bullets were live or rubber. Demonstrations were also reported elsewhere around the country.
The protests are the first serious demonstrations in sub-Saharan Africa since a wave of anti-government protests swept leaders in Tunisia and Egypt out of power.
Ugandan President Yoweri Museveni has vowed that his government will not be taken down by protests.
The violence came one day after a brutal arrest of the country's top opposition politician, Kizza Besigye. Police cracked open the window of Besigye's vehicle and doused him with tear gas at close range, before bundling him into the back of a pickup truck and speeding off.
Besigye has held five "walk to work" demonstrations to protest at rising prices and what he calls a corrupt government.