At 9:40 pm on Wednesday 26 March 1997, a grenade was thrown at the joint British Army/RUC base at Coalisland, blowing a hole in the perimeter fence. The RUC reported that a 1 kg device hit the fence off the ground. Another source claimed that the device was a coffee-jar bomb filled with semtex. The grenade was thrown or fired by two unidentified men. At the time of the attack, there was an art exhibition at Coalisland Heritage Hall, also known as The Mill, from where the explosion and the gunshots that followed were clearly heard. The incident lasted one to two minutes.