Ng describes an unusual scenario. A lot of mass shooters start out psyching themselves up -- they start outside their kill zone and come into it, and then start killing. Bishop did something less common; she went to the meeting as normal, but half an hour or so into it she produced a 9 mm pistol (make and model unknown) and began shooting. There were reportedly eleven (NEW YORK POST) or twelve (ABC NEWS) people, besides Bishop, in the room. She shot six of them at very close range, and went for headshots. Three died. Two were, at last report, in critical condition. One has been released from the hospital.
The other five people who were in the room dove to the floor, using the table as concealment. (Remember the difference between cover and concealment? Cover stops a bullet. Concealment doesn't.) Professor Debra Moriarity, reportedly Bishop's closest friend on campus, tried to crawl out of the room but was stopped by Bishop, who pointed the gun at Moriarity and pulled the trigger. The gun didn't fire. Moriarity recalls that Bishop pulled the trigger again, with the same result, which suggests a double-action or DA/SA semi-auto (a single-action, like a 1911, or striker-fired semi-auto, like a Glock, would have gone click once and required cocking or racking of the slide before the trigger could be pulled again). According to Ng, at this point Moriarity led the faculty in a rush that pushed the still-armed Bishop out the door. They then barricaded the door so Bishop couldn't get back in, and called for help. The barricade had been employed with varying degrees of success at VA Tech, and may have been especially effective here because Bishop's targets were people she knew -- with them out of reach, she had little desire to shoot anyone else, so dropped the gun in a bathroom and called her husband for a ride home.
Note what happened here: classic OODA Loop stuff. The faculty was not prepared for an armed assault, so had difficulty orienting themselves and deciding what to do -- but Bishop wasn't prepared for her gun to run dry, and apparently hadn't practiced clearing a malfunction, so she was thrown out of her own OODA Loop, which gave Moriarity and the faculty and opportunity to move against her.