Kabul, Afghanistan ? Mistaking each other for the enemy, Afghan police fired four dozen grenades and U.S.-led coalition troops fought back with helicopter gunships in a fierce battle that left eight officers dead before dawn Tuesday, officials said.

The deadly lapse in communication underscored the wide gaps – and apparent mistrust – between U.S. and Afghan security forces. President Hamid Karzai’s office called the deaths “a tragic incident” caused by a lack of cooperation and communication.

U.S. officials have said they are wary of telling Afghan forces about nighttime raids by U.S. Special Forces, the kind of operation apparently being conducted early Tuesday, out of fear the target might be tipped off.

The U.S.-led coalition said a joint coalition-Afghan force on a mission against a suspected Taliban safehouse was fired on first and responded with their own weapons, then summoned air support. It said no U.S. casualties were reported.

A presidential spokesman also said police initiated the shooting, but officers at the isolated post on a barren stretch of desert in the eastern province of Nangarhar said U.S. troops fired first.

“The Americans came close to our checkpoint with the lights of their vehicles off,” said Esanullah, commander of the roadblock. “We shouted at them to stop, but they didn’t, and they opened fire on us.” He said eight policemen were killed and four wounded.

Officers at the post fired 49 of their 50 rocket-propelled grenades and called for assistance from reserve police during the three-hour firefight, said Esanullah, who goes by one name.

Karzai’s spokesman, Karim Rahimi, said the incident underscored why the president has repeatedly called for increased cooperation between Afghan and international troops, which would help solve the problem of civilian casualties in Afghanistan.

“The police forces were not aware of the coalition’s operation,” Rahimi said. “The police checkpoint in the area thought that they were the enemy, so police opened fire on the coalition, and then the coalition thought that the enemies were firing on them, so they returned fire back.”