A police Land Rover was set on fire after being attacked by petrol bombers in Londonderry on Sunday.
A car burned out during the violence
The attack happened near a community centre at Drumleck Drive in the Shantallow area at about 2000 GMT.
Firefighters said they put the fire out, but had to withdraw when they were attacked with bottles and bricks.
Fire officer Terry Morrison said crews had no alternative but to pull out from what he described as a "life-threatening situation".
"Once anything like that occurs, we have to think of the safety of our personnel," he added.
On Saturday, a police officer was injured when a crowd attacked two patrol cars in Shantallow.
Up to 20 youths were involved in that attack.
Officers used CS spray after the group attacked two patrol cars and tried to drag them from their vehicles.
The incident happened at about 0030 GMT in the Mosspark and Glengalliagh Road areas. The policeman was later treated for a hand injury.
A 20-year-old man has been charged in connection with the incident and will appear in court later this month.
He will face charges of disorderly behaviour, assault on police and resisting arrest in connection with the incident.
A second man who was arrested at the scene escaped from police.
Officers say the man is still wearing handcuffs on his wrists.