Guns were seized for examination today after a schoolboy was hit in the head by a stray bullet.
Police took possession of at least ten .22 rifles in a bid to identify the owner of the weapon which fired the shot which left five-year-old Darragh Summers critically ill.
Officers are also studying a list of registered firearms holders.
They believe it was a bullet from somebody out shooting for vermin on neighbouring land which accidentally hit the boy in the back of the head as he played with 180 other children in a school playground near Enniskillen, Co Fermanagh.
Surgeons removed a .22 bullet from Darragh's head and ballistic tests will be carried out.
Police tonight urged all licence holders owning similar calibre weapons to hand them over.
A spokesman said: "We would prefer people come forward rather than us going looking for them."
High land and fields close to St Patrick's Primary School at at Mullinaskea is popular for the shooting of foxes, rabbits and crows, and its understood people are also investigating a report of sheep worrying.
The bullet which hit Darragh has a range of up to 300 yards.
His school was closed today as staff and pupils after the shooting which came at Friday lunchtime.
Headmaster Brendan O'Connor: "There have been a lot of tears and sadness. Nobody could ever imagine something like this could ever happen at a school playground."
Experts from the Western Education and Library Board are helping teachers prepare for the resumption of classes.
A special Mass is being held tonight for Darragh as his parents keep a bedside vigil at the Royal Belfast Hospital for Sick Children. They also believe the shooting was accidental.
The family's priest, Father John Halton said: "They cannot imagine that anyone consciously shot the boy. They feel quite the opposite, that it was an accident of some kind."
He said: "That's given them some kind of confidence. They spoke with sympathy about the innocent person who they believe was involved in an accident and may not even know it yet.
"They would like that person, when they hear the news, to come forward. It would give great peace of mind to them and it would also give great peace of mind to the parents and children of the school. "It would get rid of any fear that is around."
PA