Kelen, G.D., Catlett, C.L., Kubit, J.G., and Hsieh, Y.H. (2012). Hospital-Based Shootings in the United States: 2000 to 2011. (Abstract only.) Annals of Emergency Medicine. 60(6):790-798.
The authors analyzed reports on acute care hospital shooting events in the U.S. from 2000-2011 and found 154 incidents in 40 states, resulting in 235 injured or dead victims. They provide additional demographic data (e.g., perpetrator characteristics, location of shooting).