U.S. forces may have mistakenly bombed a hospital in northern Afghanistan on Saturday, killing at least 19 people, including three children, in an incident that will likely raise new questions about the scope of American involvement in the country’s 14-year war. The United Nations’ top human rights official called for an independent investigation, while equating the airstrike on the hospital to a war crime. “This event is utterly tragic, inexcusable, and possibly even criminal,” Zeid Ra’ad al-Hussein, the U.N. High Commissioner for Human Rights, said in a statement.