A protest by Zimbabwean taxi drivers against a police crackdown turned violent when residents in the capital, Harare, joined in and hurled rocks at police, who fired tear gas and water cannon to disperse the rioters.
Taxi and minibus drivers, along with company owners, accuse police of corruption, saying that they raise money for their operations by imposing hefty fines on their vehicles.
In the past month, amid rising unrest over economic woes, Zimbabwe has witnessed spontaneous protests against government corruption, shortage of money and government plans to circulate local bank notes.
The protesters closed roads and burned tyres in the eastern part of Harare on Monday, as local youth engaged in running battles against armed police wearing riot gear.
Officers responded with batons, tear gas and water cannon to disperse the crowds. Some schoolchildren were caught up in the violence as well.
Police spokeswoman Charity Charamba told reporters that anti-riot police were deployed in two townships outside Harare and arrested 30 people in connection with the violence.
The southern African country is facing a cash crunch resulting in banks running out of notes. The government has failed to pay June salaries to the majority of its workers.
Without public transport, many residents in Harare were forced to walk to work on Monday. More protests are scheduled for Wednesday.
Monday's clashes come days after residents protested in the border town of Beitbridge, 600km south of Harare, last Friday against restrictions on imports of basic goods from South Africa.
Zimbabwe has suffered years of economic decline and mass emigration since President Robert Mugabe took power in 1980, when the country won independence from Great Britain.