Parents urged to keep children in amid Londonderry disorder
Police said youngsters were involved in the trouble.
Disorder has flared in Londonderry for a sixth successive night.
Youths in the city’s Bogside have thrown petrol bombs at police and random passing vehicles and also lit a fire on a main flyover.
The disturbances in the republican neighbourhood come on a day when the city hosted Twelfth of July Orange Order commemorations.
Youths wearing hoods and masks, some of them of a very young age, were among a crowd of around 200 that gathered as trouble erupted in Bogside.
At one point a teenager hurled a petrol bomb at the windscreen of a passing van from point blank range.
The majority of the petrol bombs have been aimed at police stationed on the historic city walls overlooking the Bogside.
The Police Service of Northern Ireland said: “We regret to say that we are experiencing further disorder in the area of the Bogside with a number of petrol bombs already thrown at police.
“There is a large crowd gathering. It is clear that there are young children involved. Parents – make sure your children aren’t involved.”
It is the sixth night of violence in the area.
This week has already witnessed two dissident republican murder bids against police officers in Derry.
On Tuesday night a volley of machine gun fire was directed at officers and on Wednesday night two pipe bombs were thrown at police. No one was injured.
As well as police, rioters have also targeted homes in the nearby unionist Fountain estate.
Wednesday night also brought violent scenes in Belfast, with loyalists blamed for the disorder.
Masked men hijacked and torched vehicles amid anger about moves to reduce the size of two loyalist Eleventh Night bonfires.
Thousands of Orange Order members took part in Twelfth of July parades across Northern Ireland on Thursday to mark the 1690 victory of Protestant King William of Orange over Catholic King James II at the Battle of the Boyne.
It is the biggest date in the Protestant loyal order parading calendar.