A U.S. service member and an American civilian died early Tuesday in an attack in Afghanistan, the Pentagon has announced. Three other Americans, including one who is a service member, sustained wounds in the incident outside a coalition base near Kabul. The gunman, reportedly an Afghan solider, was later killed. “Our people were visiting the site as part of their train, advise, assist mission,” a defense official said. “A lone assailant opened fire on them at the entry control point.” An investigation has been opened into the incident. “Any time we lose a member of our team, it is deeply painful,” said Gen. John W. Nicholson, commander of U.S. Forces-Afghanistan and Resolute Support. “Our sympathies go out to the families, loved ones, and the units of those involved in this incident.” The Defense Department has not disclosed the identities of those killed, pending notification of their families.

According to the defense official, the attack occurred near Camp Morehead, an ammunition depot and home to U.S. Special Forces, at around 11 a.m. local time. The camp is just north of Kabul. This is the first time two have been killed this year. In all, there had been three U.S. combat deaths this year. If indeed the incident turns out to be an attack by an Afghan soldier, it will be the first such attack, which the military calls green on blue, since 2015. — Nancy A. Youssef