The attack was reported on Tuesday, 21 November when a number of sheep were found injured on a farm in Shanlongford, Co Derry.
It is thought that a group of dogs attacked the sheep. The sheep were seriously injured and some were subsequently put down as a result of the attack.
This incident follows a number of attacks on sheep across the island, with many farmers increasingly worried by dog attacks.
Police at Limavady are appealing for anyone who might have witnessed the attack to contact them on 101, quoting the reference number 276.