CHICAGO - US Secretary of State John Kerry stopped in Chicago on Monday on his way home from Asia to visit the family of a young US diplomat who was killed in Afghanistan earlier this month.

Anne Smedinghoff, 25, was killed along with four other Americans in a car bomb blast on April 6 in the southern province of Zabul. Her parents live near Chicago.

Returning after a 10-day trip to the Middle East, Europe and Asia, Kerry descended from his Air Force plane at Chicago's O'Hare airport and walked to a building off the tarmac to meet Smedinghoff's parents and siblings.

The State Department described the roughly one-hour meeting as "private" and media were not permitted to enter the building. Kerry had met Smedinghoff in late March in Kabul, where she was one of the embassy staff helping to organize his visit.

"Everybody understands and feels that kind of a loss," Kerry told employees at the US Embassy in Tokyo, Japan, before leaving for Washington.

He said the Americans had been on their way to donate books to children.

"Twenty-five-year-old young woman, full of idealism, full of hopes, taking books to children in a school so they could learn. And wiped out by terrorism, by the worst kind of nihilism."

Smedinghoff had volunteered for the assignment in Afghanistan, where she served as an assistant information officer. Before that, she had been assigned to Caracas, Venezuela.