In pictures: Clashes in Ferguson
Police fired tear gas to disperse angry crowds ahead of a second night under curfew in the US town of Ferguson, in the state of Missouri.
Protesters were on the streets in the lead-up to the curfew, angry over the shooting of an unarmed black teenager last week.
This is the eighth consecutive day of protests since the death of 18-year-old Michael Brown on 9 August.
The curfew, in force from midnight to 05:00 local time (05:00 GMT - 10:00 GMT), was imposed after previous protests had turned violent.
A preliminary private autopsy found that Mr Brown was shot at least six times, including twice in the head, according to the New York Times.
Tensions between police and protesters had risen on Sunday night, with police saying petrol bombs and bottles had been thrown at them.
Police say they had "no alternative but to elevate their response".
Police responded to an alleged advance on police officers by firing rubber bullets and tear gas canisters at the crowds.
Following the escalation of the violence, the US state of Missouri is sending in the National Guard in an attempt to restore order.