Colombia: TransMilenio bus protests paralyse Bogota
Public transport in the Colombian capital Bogota has been paralysed by protests for improved services and lower fares on the main bus network.
Hundreds of people - many of them students - occupied bus stations on the TransMilenio network.
Police used tear gas and water cannon after some protesters threw stones and vandalised facilities.
Bogota Mayor Gustavo Petro blamed left-wing parties for the disturbances, but they have denied involvement.
"What began as a peaceful protest with chants and placards and against the deficiencies in TransMilenio turned little by little into acts of violence," the mayor's office said in a statement.
"The order for the police is to guarantee the service; the order for TransMilenio is not to stop the service under any circumstances," Mr Petro said.
Police in riot gear clashed with protesters who blocked several of Bogota's main roads, causing chaos for commuters.
Dozens of people were detained.
Mr Petro lifted restrictions on car use and allowed other buses to use routes normally reserved for TransMilenio to help people get home from work.
The protesters say the TransMilenio network is overcrowded, over-priced and beset by delays.
Mr Petro - who was elected mayor last October - has promised to improve the service and give passengers a greater say in how it is run.
First opened in 2000, the TransMilenio mass transport system is a network of dedicated bus lanes and passenger terminals served by high-capacity articulated buses.