PANJWAI, Afghanistan — Displaced by the war, Abdul Samad finally moved his large family back home to this volatile district of southern Afghanistan last year. He feared the Taliban, but his new house was nestled near an American military base, where he considered himself safe.

But when Mr. Samad, 60, walked into his mud-walled dwelling here on Sunday morning and found 11 of his relatives sprawled in all directions, shot in the head, stabbed and burned, he learned the culprit was not a Taliban insurgent. The shooting suspect was a 38-year-old United States staff sergeant who had slipped out of the base to kill.

The American soldier is accused of killing 16 people in all in a bloody rampage that has further tarnished Afghan-American relations and devastated Mr. Samad, a respected village elder whose tired eyes poured forth tears one minute and glared ahead in anger the next.

Once a believer in the offensive against the Taliban, he is now insistent that the Americans get out. “I don’t know why they killed them,” said Mr. Samad, a short, feeble man with a white beard and white turban, as he struggled in an interview to come to terms with the loss of his wife, four daughters between the ages of 2 and 6, four sons between 8 and 12, and two other relatives.