A number of homes were evacuated after an explosive device was found outside a house.
Police are appealing for information following the discovery of the suspicious object in the Hollymount Park area of Londonderry at 8.15am.
An Army bomb disposal team examined the object, which was later declared to be a crude viable explosive device.
The area was declared safe at around 12.30pm.
Pat Ramsey, SDLP MLA for Foyle, condemned the actions of those responsible for the explosive.
"The discovery of a crude and viable device by the PSNI reminds us of those who would recklessly endanger the lives of people in this community," he said.
"It is welcome that the device was intercepted before it could cause any damage or potential loss of life.
"Leaving such a device in a densely-populated area is utterly reprehensible and must have been a frightening experience for those who were evacuated from their homes.
"I would urge anyone who has any information regarding this incident to come forward to the PSNI."