Two-thirds of all mass public attacks in the United States last year were carried out by someone with mental health problems. In more than one-third of the attacks, the attacker killed himself at the site of the attack or shortly after leaving. Those findings come from a new report from the country’s National Threat Assessment Center (NTAC). The NTAC is part of the United States Secret Service. The researchers looked at 27 attacks in public spaces in which three or more people were injured or killed. The attacks took place in 18 states. Ninety-one people were killed in all. Another 107 were wounded. Such attacks included the February 2018 high school shooting in Parkland, Florida, which left 17 people dead. The researchers also looked at the October 2018 shooting at the Tree of Life Jewish religious center in Pittsburgh, Pennsylvania. Eleven people died in that attack. U.S. officials are searching for ways to decrease such violence.