WASHINGTON - U.S. officials say it was an American Army soldier who may have shot as many as 16 Afghans before dawn on Sunday in southern Afghanistan.
Officials say the U.S. military there is treating at least five wounded.
Caitlin Hayden, a spokeswoman for the White House National Security Council, said that President Barack Obama had been briefed on the incident. She said, "we are deeply concerned by the initial reports of this incident, and are monitoring the situation closely."
Defence Secretary Leon Panetta also has been informed of the incident.
NATO had confirmed earlier on Sunday that a U.S. service member had been detained, while Afghan officials reported that 16 people were killed including nine children and three women.