A controlled explosion has been carried out on a bomb at a house on the Waterside, Londondery.
Police attended the scene after a suspicious object being thrown into the rear yard of a house in Ebrington Street at about 12.10am on Friday morning.
The Army attended and a controlled explosion was carried out just after 5.30am.
The object was declared to be a viable pipe bomb-type device.
A number of houses were evacuated in the loyalist-dominated area.
The Clooney Centre was made available for anyone in need of shelter.
By 9am, the PSNI said residents are able to return to their homes.
Emerson Street and Bond Street were closed to traffic for a while but have now reopened.
Detective Sergeant Brian Reid said in a statement: “I would ask anyone with any information about this incident to contact detectives at Strand Road Police Station on the non-emergency number 101. Or if someone would prefer to provide information without giving their details, they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.”