Police in Chile's capital, Santiago, have arrested about 100 people in a fresh protest against a new public transport system.
The protest was organised by university and high school students
Riot police fired water cannon and tear gas to disperse protesters, some of whom were throwing stones.
The Transantiago network was intended to simplify the system and modernise buses but hundreds of routes have been cancelled or diverted.
More than 800 people were arrested in similar protests last week.
President Michelle Bachelet had appealed for calm after the first demonstrations.
Wednesday's protest was organised by university and high school students.
They say the new system has hit lower-class neighbourhoods, leaving many people with few or no services.
Ms Bachelet has admitted mistakes were made and appointed economist Rene Cortazar as the new transport minister.
Mr Cortazar on Tuesday announced several changes to routes.
He met a deputation from the protesters at the transport ministry building.
Last Thursday the issue raised tension at the annual Day of the Young Combatant march.
The day marks the anniversary of the 1985 killing of two students by police during a demonstration against the military government of General Augusto Pinochet.
A total of 38 police officers were hurt as they battled stone-throwing protesters, authorities said.