Petrol bombs and other missiles have been thrown at police during an illegal republican parade in Londonderry.
Officers were in an armoured police Land Rover in the Creggan area of the city where the parade began when they were targeted shortly after 14:00 BST.
The parade was led by more than a dozen people in paramilitary-style dress.
It ended at Derry's City Cemetery where about 300 people are taking part in an event to commemorate the anniversary of the 1916 Easter Rising.
A group of youths wearing masks set fire to bins and blocked one of the main roads leading into Creggan.
A police helicopter flying overhead is monitoring developments.
The Police Service of Northern Ireland (PSNI) said that none of its officers had been injured in the attack and it appealed for calm.
DUP MLA Gary Middleton tweeted: "This reckless behaviour is an attempt to cause harm not only to PSNI officers but to our communities as well.
"There must be swift action to bring those responsible to justice."
Last week the PSNI said there was potential for public disorder over Easter, with "very strong intelligence" suggesting dissident republicans were planning attacks in Derry.
Chief Constable Simon Byrne had said the disorder could be an attempt to draw officers into gun or bomb ambushes.
https://www.bbc.co.uk/news/uk-northern-ireland-65231790
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