1. Chief O'Brien is at Ops when he is shot with a phaser by an alien intruder; later, after sustaining injury, a Klingon holding him hostage injures him further by kicking him back onto the floor.
From Quiz Name That Episode #2
Answer:
Invasive Procedures
After the group consisting of the Trill, his female alien lover and his two Klingon accomplices board the station, they hold the senior staff hostage at Ops. The Trill sets a example of how serious the situation is by landing a phaser shot to O'Brien's shoulder. Later, when the still-injured O'Brien, Kira and Sisko are discussing Dax's chances of survival, one of the Klingon guards (played by the very-talented Tim Russ, no less!) who's gotten tired of hearing all the talking takes his anger out on O'Brien by kicking the station's chief engineer and knocking him to the floor, re-injuring the phaser-burned shoulder. In "Tribunal", it's true that O'Brien was shot by a blast from one of the Cardassians' hand-held weapons, but he was onboard the runabout and not onboard the station when that happens. In "The Way Of The Warrior", even though the Klingons do end up boarding the station and stunning several security personnel with their hand-held weapons, O'Brien is fortunately not one of the targets of the weapons fire. Then in "By Inferno's Light", there were no Klingons holding anybody hostage; their military presence on the station was agreed upon by Sisko and Gowron.