CHICAGO (AP) — Shootings and other traumatic events involving children are not rare events, but there's a startling lack of scientific evidence on the best ways to help young survivors and witnesses heal, a government-funded analysis found.

School-based counseling treatments showed the most promise, but there's no hard proof that anxiety drugs or other medication work and far more research is needed to provide solid answers, say the authors who reviewed 25 studies. Their report was sponsored by the federal Agency for Healthcare Research and Quality.

According to research cited in the report, about two-thirds of U.S. children and teens younger than 18 will experience at least one traumatic event, including shootings and other violence, car crashes and weather disasters. That includes survivors and witnesses of trauma. Most will not suffer any long-term psychological problems, but about 13 percent will develop symptoms of post-traumatic stress, including anxiety, behavior difficulties and other problems related to the event.