Mass casualty incidents, particularly mass shootings, are a serious issue in the United States. These incidents have increased over the past two decades and more than 32 public mass shootings have occurred since 2016, with approximately 12.8 incidents occurring each year. Since 1966, there have been over 1,202 fatalities and countless injuries due to public mass shooting incidents. Therefore, it is essential that professional counselors are equipped to treat primary, secondary, and tertiary victims of these incidents. The purpose of this article is to examine the current literature on public mass shootings, including psychological consequences, treatment considerations, ethical and legal issues, and cultural factors. Vicarious traumatization and self-care are also explored. Recommendations for training and resources are offered, and implications for professional counselors and counselor trainees are discussed.