KABUL, Afghanistan (CNN) -- A coalition warplane bombed an Afghan police outpost during a battle with suspected Taliban fighters early Wednesday, killing six officers in what a U.S. military spokesman called "a tragic case of mistaken identity."
"Coalition forces deeply regret the incident of mistaken fire," Colonel Jerry O'Hara, a spokesman for the U.S. military in Afghanistan, said in a statement outlining the attack.
At least one other Afghan died in the incident, which occurred about 120 kilometers (75 miles) northeast of Kandahar in Zabul province, the U.S. military reported.
Among the dead was the commander of an Afghan national police detachment, while 11 other police officers were wounded, said Gholam Jailani Sarahi, the province's deputy police chief.
The U.S. military put the number of wounded at 13.
The U.S. command in Kabul said its raid was aimed at a "known insurgent commander" in Zabul, one of the hotspots in the seven-year-old war in Afghanistan -- the original front in the war on the al Qaeda terrorist network and its Taliban allies, launched after the 2001 attacks on New York and Washington.
During the raid, an armed fighter holed up in a building took on coalition troops and was killed. Then the allies began taking rifle and rocket-propelled grenade fire from a nearby compound, prompting the airstrike.
They later found those firing on them were Afghan police from the compound.
"Initial reports indicate this was a tragic case of mistaken identity on both parts," O'Hara said.
Sarahi said Taliban fighters had fired rockets at the police post, located near the provincial capital Qalat. The U.S. military said a joint investigation was being conducted with Afghan military and police officials.
Allied airstrikes have become a point of friction between the U.S.-led alliance battling a resurgent Taliban and the government of Afghan President Hamid Karzai. Karzai said in November that his "main and first demand" of the incoming U.S. administration would be to stop civilian deaths from the raids.
Journalist Farhad Peikar contributed to this report.