Police have been attacked with petrol bombs after finding a suspicious object in the Creggan area of Londonderry.
Around 80 officers had been searching for bomb-making equipment on Monday, targeting dissident republicans in the Northern Irish city.
It followed the discovery of an improvised explosive device in Strabane during the weekend which has been linked to the New IRA.
Police said the mortar was near a family home and was aimed at the local police station.
In Derry on Monday, officers were targeted while carrying out searches and around 15 homes were evacuated to keep residents safe, police added.
PSNI Assistant Chief Constable Mark Hamilton described the operation around the suspicious object as "complex".
He added: "This is a complex operation which is expected to continue throughout the night and we have advised those residents who have left their homes to make alternative arrangements."
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"We recognise the upheaval this has caused and we are grateful for their co-operation and understanding.
"The focus of this operation is ensuring the people of Creggan are safe however it is concerning to see significant numbers of young people on the streets, late into the night, throwing petrol bombs and other missiles at officers in the area.
"The reality is this type of disorder contributes to the complexity of the policing operation and presents a real risk of injury to those involved.
"Already we have seen two incidents this evening where young people have sustained burn injuries as result of engaging in disorder.
"I would reiterate our appeal for those young people to return home and remove themselves from the situation.
"We are grateful for the support of community representatives in helping to reduce tensionsRead More – Source