Police in Northern Ireland say they have arrested five people in connection with the April killing of a police officer.

Authorities said Tuesday the five suspects were arrested under an anti-terror act during an operation that involved around 200 officers.

The 25-year-old policeman was killed April 2 outside his home in the town of Omagh when a bomb exploded under his car.

Police had already charged one person in connection with the bombing.

A 1998 peace accord largely ended three decades of violence in Northern Ireland between pro-Irish and pro-British forces.