PSNI officers were attacked while dealing with two security alerts in the Creggan area of Derry last night.
Between 40 and 50 people threw petrol bombs and other missiles after police and army bomb officers were called after a pipe bomb was thrown through the window of a car on Circular Road at around 8.30.
A short time later, another device was found in a car in Iniscairn Crescent. Both devices failed to explode.
A significant security was maintained in the area overnight, and investigations are continuing with both devices taken away for further examination.