U.S. emergency room doctors treat a gunshot wound every half-hour, a new study has found. What's more, firearm injuries appear to follow specific patterns throughout the year, with gun violence occurring more often at certain times, according to research from the U.S. Centers for Disease Control and Prevention. Firearm injury Emergency Department visit rates were highest during evenings, weekends, summer months and holidays, noted the research team led by Dr. Adam Rowh , an epidemic