On 11 February 1990, an active service unit of the Provisional IRA East Tyrone Brigade shot down a British Army Gazelle helicopter (serial number ZB687) along the border between Northern Ireland and the Republic of Ireland. It took place between Augher in County Tyrone and Derrygorry in County Monaghan. The helicopter was hit several times by heavy machine-gun fire and crash-landed on an open field, injuring three members of its crew of four.