Four police officers were injured overnight when they were attacked with bottles and bricks by a mob of around 30 people in Belfast.
Two shots were fired in a bid to calm the violence in the north of the city, during which a policewoman was struck in the face with a bottle.
The trouble started after four men got out of a car and threw missiles at Tennant Street police station, shortly after 1am.
They drove off into Montreal Street, followed by two police officers but abandoned their vehicle and were eventually pursued on foot. Minutes later, one of the suspects grabbed the policewoman and hit her in the face with a bottle.
A hostile crowd emerged from a local pub and surrounded the officers, who managed to return to their vehicle but were unable to start it.
The vehicle then came under a hail of missiles and was seriously damaged as the officers waited on reinforcements to arrive.
A PSNI spokeswoman said two shots were fired as police attempted calm the disturbance. Four officers were hurt, but their injuries were not serious.
One man has been arrested in connection with the trouble. Afterwards, a van was set on fire in Cambrai Street.
Elsewhere, a police Land Rover was set on fire in Derry as officers came under attack with petrol bombs and other missiles.
Police had been called to an incident in Drumleck Gardens yesterday evening. A number of men forced their way into a house and threatened the occupants. One man was arrested.
A PSNI spokeswoman said no one was injured in the trouble, which ended at around 9pm.