The linked article states:
Of the incidents that were stopped by people at the scene (as opposed to incidents where the shooter was not resisted in any way) 2/3 of the shooters were stopped by citizens, However, those facts are not correct. Here's some definative information on the subject--
In the newly released book, Active Shooter Events and Response by Dr. J. Pete Blair, the 264-page volume includes a chapter devoted to Blair's in-depth research of 84 active shooter cases that occurred in the US between 2000 and 2010. Active shooter events (ASEs) were most likely (37%) to erupt in a business setting (factory, warehouse, office, retail outlet), followed closely by schools (34%).
A pistol was the most powerful weapon used in the majority [ 60% ] of ASE’s. Rifles were the next most popular weapons deployed in 27% of the attacks. In about 40% of cases, shooters carried multiple weapons. Only 2% brought explosives to attack the location. The median time from first reporting to the event ending was 3 minutes. By 9
Minutes 73% had stopped shooting.
49% of the time the shooting has stopped by the time law enforcement arrived. In about half those instances, the subject killed himself. About 4 % of the time, they fled. In the remaining cases, people on scene subdued or shot the shooter.
84 Active Shooter Events (ASEs) occurred between 2000 and 2010. The frequency of ASEs appears to be increasing. Business locations were the most frequently attacked (37%), followed by schools (34%), and public (outdoor) venues (17%). The median number of people killed during ASEs is 2. The median number shot is 4. The most commonly used weapon was a pistol (60%), followed by rifles (27%), and shotguns (10%).
Attackers carried multiple weapons in 41% of the attacks. Body armor was worn in 4% of cases. Improvised Explosive Devices (IEDs) were brought to the scene in 2% of cases. Some shooters attempted to deny police access to the attack site through the use of barricades. The attacks ended before the police arrived 49% of the time. In 56% of the attacks that were still ongoing when the police arrived, the police had to use force to stop the killing. EMS entry to the attack site is often delayed because the police must conduct a thorough search of the scene in order to declare it secure.