Four men have been arrested after a bomb was found in Northern Ireland shortly before a visit by Hillary Clinton.
Police said the viable bomb was discovered after officers investigating dissident republican activity stopped a car in Londonderry - the UK's City of Culture for 2013.
Witnesses said police rammed the vehicle in the Westway area of Creggan at about 8.40pm on Thursday. The army bomb disposal unit was called in after officers became suspicious about contents in the car.
A spokeswoman for the Police Service of Northern Ireland said: "Detectives from the serious crime branch investigating ongoing dissident republican activity in the Londonderry area arrested four males in the Creggan area of the city last night.
"At approximately 8.40pm, police stopped a car and subsequently arrested two males aged 47 and a male aged 40 after the discovery of what is believed to be a viable IED (improvised explosive device). A fourth male aged 41 was arrested nearby."
All four suspects were taken to the PSNI serious crime suite in Antrim for further questioning.
The discovery of the bomb comes ahead of a visit by US secretary of state Mrs Clinton, who is due to meet Northern Ireland's First and Deputy First Ministers at Stormont. Mrs Clinton's husband, former US president Bill, was a key player in the peace process during the 1990s.
It is understood the men who have been arrested are well-known dissident republicans from the Co Londonderry area.
SDLP Foyle MLA Pat Ramsey said people were angry at the disruption caused by this latest bomb alert. He said: "Once again, the people of the Creggan are the victims of disruption, distress and anger. People are genuinely fed-up with this. And this may have something to do with it because the dissidents have consistently said we will not have anything resembling normality during the UK City of Culture year.
"It was freezing cold last night and there were people in their 80s and 90s who were moved from their home. Some forgot medication. The people they tell us they represent are the people who are being disrupted. This has to stop. Thank God the police found the bomb and the people of this city or somewhere else are not waking up to destruction today."