London, England (CNN) -- Police in Northern Ireland evacuated a school Monday after a child found an explosive device and brought it into a classroom, police said.
They evacuated a second school nearby shortly afterwards when a warning was phoned to a local media outlet, they said.
Chief Inspector Simon Walls called the incident "beyond despicable. It is by sheer good fortune that we are not dealing with a severely injured child right now."
Walls said "cowardly criminals" were behind the incident and called on local people "to enable us to efficiently and effectively alienate those who continue to be involved in terrorism and criminality."
Both schools were in the town of Antrim, north of the Northern Ireland capital Belfast.
No one was injured and the device was made safe, the police said.
Northern Ireland was the scene of frequent violence between pro-Irish and pro-British forces over a period of three decades known locally as the Troubles. About 3,000 people were killed before a power-sharing deal known as the Good Friday Agreement in 1999.
CNN's Anna Stewart and Richard Allen Greene contributed to this report.