(CNN) Multiple Afghan security forces personnel were killed by US airstrikes this week while trying to come to the defense of Afghans under attack by the Taliban in Helmand province, a spokesman for the US military in Afghanistan told CNN.

While the Afghan national defense forces were under heavy attack by the Taliban late Thursday, they requested precision air support and airstrikes were called in, according to Col. Dave Butler. He said US authorities coordinated with the Afghans to make sure the area was clear of friendly forces and were told that it was.

"Unfortunately, they were not and a tragic accident resulted. Afghan Security Forces as well as Taliban fighters were killed in the strikes," Butler said.

The New York Times and Washington Post first reported the incident.

Eight Afghan policemen were killed and 11 others were injured when Taliban attacked checkpoints in Helmand, according to a spokesman for the Afghan Interior Ministry, Nasrat Rahimi. He did not provide any figures about casualties during the airstrikes.

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