(CNN) - Seven American service members were among the 11 people killed in a helicopter crash in southern Afghanistan on Thursday, NATO's International Security Assistance Force said.
Three members of the Afghan National Security Forces and an Afghan civilian interpreter also died in the crash of the UH-60 Black Hawk helicopter.
The cause of the crash is under investigation, the ISAF said.
The helicopter had been on patrol when it went down in the Chinarto area of Shah Wali Kut district in Kandahar province, the Kandahar governor's office said in a news release.
It is not clear whether the helicopter was in the area because of military operations, the office said.
The crash comes two days after one of the bloodiest days in Afghanistan so far this year, with three separate attacks leaving at least 47 people dead and at least 145 wounded, according to government and police officials.
Six other helicopter crashes involving Operation Enduring Freedom, the official name for the U.S. operation in Afghanistan, occurred this year, according to a CNN count. Sixteen Americans died in five crashes: six died in January, four in April and two each in May, June, and July. Four of the crashes occurred in Afghanistan and one in Oman.
And in March, 12 Turkish service members died in a helicopter crash in Kabul province.
Last August, 30 Americans and eight Afghans died when the Taliban downed a helicopter near Kabul. Of the 30 killed, 22 were Navy personnel. Seventeen of them were members of the SEALs, the unit that conducted the raid that killed al Qaeda leader Osama bin Laden at a compound in Pakistan.
The other eight U.S. troops killed were three Air Force forward air controllers and five Army helicopter crew members.
