Hospital shootings are relatively rare events, according to a study published Sept. 18 by the Annals of Emergency Medicine (PDF).

The study, conducted by Johns Hopkins-affiliated researchers, found that a person is more likely to be killed by lightning than shot in a hospital or in its parking lot. Researchers studied newspaper articles and news releases published from Jan. 1, 2000, through Dec. 31, 2011, to arrive at its hospital-related results.

The research indicates that 3% of acute-care hospitals in the U.S. experienced at least one shooting event in the 12 years studied, producing a rate of 0.2% a year, findings that are consistent with Labor Department data, researchers wrote.

Among the hospital shootings that do occur, 59% occurred inside the hospital and 41% on hospital grounds, with 29% of the total taking place in the emergency department. Twenty-three percent of the shootings in the ED involved a security officer's gun taken by the shooter.

The authors note that metal detectors, while often called for after a hospital shooting, would have prevented only 30% to 36% of the shootings.

Nonetheless, hospital violence is a real concern, with the rate of assaults on healthcare workers at four times that of private sector industries, researchers wrote.

The study was conducted in response to a shooting at a Johns Hopkins facility, where staff members were feeling vulnerable, researchers wrote. In September 2010, a man at Johns Hopkins Hospital shot and killed his 84-year-old mother in her hospital room, shot her physician (who survived the attack), and then committed suicide. Other high-profile attacks have occurred at hospitals across the country.

The researchers hailed from the Johns Hopkins Office of Critical Event Preparedness and Response, part of Johns Hopkins Institutions; the National Center for the Study of Preparedness and Catastrophic Event Response, part of Johns Hopkins University; and the Department of Emergency Medicine at Johns Hopkins University School of Medicine, all in Baltimore.