Nine men were in custody tonight after a massive police search for weapons and explosives linked to dissident republicans in Northern Ireland.
Later, officers involved in the investigation were attacked by youths throwing petrol bombs and stones in Craigavon, Co Armagh.
At one stage there were attempts to hijack a lorry and a bus, which was set alight.
Police said nobody was injured. A shotgun and ammunition were recovered when homes were raided in Craigavon.
The operation was one of the biggest ever mounted against criminal elements in the so-called Continuity IRA (CIRA), which is opposed to the peace process, and lasted nearly 12 hours.
Houses and fields were checked in the Brownlow area of Lurgan, where there have been a number of failed terrorist attacks on police.
British army bomb disposal experts and sniffer dogs were also called in. Flats at Drumbeg and Aldervale were also searched by detectives and officers belonging to specialist tactical support groups. Police said they would try to keep unavoidable disruption to a minimum.
Chief Inspector Pauline Shields said: "This is an important and necessary operation targeting dissident republican criminals. Our aim is to make Craigavon a safer place for everyone."
Dissident republicans in north Armagh, opposed to the peace process, have been involved in a number of incidents, especially over the past two years. Police stations have been attacked and bomb-making material recovered.
There have been hoax bomb alerts on the main Belfast-Dublin railway line.
Dolores Kelly, a Craigavon councillor and an SDLP member at the Northern Ireland Assembly, said today's police action was needed.
She said: "People in these communities who are being tortured by crime and other forms of anti-social behaviour have complained about the need for a proper policing service. "But the police have been hampered because of the continuing threat by dissidents. People want them (the dissidents) off their backs."