– A NATO soldier and a civilian contractor were killed in Afghanistan Saturday, hours after the United States said joint raids with Afghan forces were returning to normal.

Saturday’s attack, which was initially reported as an apparent insider attack, also killed three Afghan troops, NATO officials said. But Sunday, NATO’s International Security Assistance Force attributed the attack to possibly insurgent fire.

The incident happened in eastern Afghanistan, NATO officials said. ISAF said in a statement that the incident occurred while an ISAF unit was manning a temporary check point in an area near and Afghan National Army unit. The statement said the shooting occurred following a short conversation between NATO and Afghan personnel. In an ensuing exchange of fire, three Afghan troops were killed.

“We deeply regret the loss of life in this tragedy,” the statement said. “Our deepest sympathies are with the families of our personnel who were killed.”

An official in Maidan Wardak province said the attack happened in a post in the province’s Sayed Abad district. Most coalition troops in the province, which is less than an hour’s drive west of Kabul, are Americans.

The Taliban, who have claimed responsibility for a number of past insider attacks through their infiltrators, described Saturday’s incident in a statement as an “internal clash” between Afghan and foreign troops.

The attack came hours after U.S. officials in Washington said joint small raids with Afghan forces were resuming after being halted early this month following an increase insider attacks, also known as green-on-blue attacks.

Dozens of Afghan forces have also died in insider attacks. But the rising toll and spread of strikes against foreign forces has touched the nerves of NATO and U.S. officials.

“I’m mad as hell about them, to be honest with you,” Gen. John Allen, the top commander of U.S. and NATO forces in Afghanistan, told CBS’ “60 Minutes” in an interview scheduled to be broadcast Sunday, according to the Associated Press. “It reverberates everywhere across the United States. You know, we’re willing to sacrifice a lot for this campaign, but we’re not willing to be murdered for it.”