A security alert in the Aileach Road area of Derry has now ended after being declared a hoax.
Police received a report around 7:10 yesterday evening of a suspicious object that had been left in the area.
While officers attended to scene to examine the object they were attacked by a large group of youths.
Petrol bombs, paint cans and pieces of masonry were thrown at police.
One officer was injured, but remained on duty.
A number of police vehicles were also damaged.
Ammunition Technical Officers assessed the object.
It has been removed for further examination.
Cordons that were in place have now been lifted.
Police are appealing for information as investigations continue.