NEW: The United States is responsible for the strike on an Iranian elementary school, an ongoing military investigation has found, according to the New York Times. Iranian officials say 175 people were killed, most of them being children. "Officers at U.S. Central Command created the target coordinates for the strike using outdated data provided by the Defense Intelligence Agency," the New York Times reported. The location of the Shajarah Tayyebeh elementary school was formerly part of an adjacent Iranian base, the investigation found. Horrific. Video: NBC News