Police were questioning three men today about dissident republican activity in Derry after a major security operation in the city.
The men were arrested shortly after 1am after they were spotted acting suspiciously on the Limavady Road.
The arrests triggered a security operation which saw three streets, Browning Drive, Clooney Park West and Clooney Park East, sealed off.
Residents were told to remain in their homes as police carried out searches.
The searches were taking place close to a former army barracks at Ebrington which has not been occupied for some time.
It is understood a passing police patrol stumbled on the three men acting suspiciously outside Ebrington Barracks.
Chief Superintendent Richard Russell confirmed: “I am not privy to all the details yet but as far as I know, police came across this activity outside Ebrington Barracks.”
Police were searching the gardens and exterior of houses in the three streets as a precautionary measure.
The chief superintendent said: “We have already started searching with police and military dogs in the area and as more specialist personnel arrive, we will be doing further in-depth searching.
“So it is a matter of degree. We have already started some searching and more will be carried out as the morning progresses.
“We have tried to minimise disruption. We have tried to keep the Limavady Road open. It hasn’t been closed at any stage so traffic is flowing quite freely.
“There is, of course, some disruption to people living in the area but we hope as we get the searching under way more fully, those people will be able to get on with their everyday lives quite quickly.”