A U.S. service member has been detained in Afghanistan, according to NATO's International Security Assistance Force (ISAF). NATO spokesman Capt. Justin Brockhoff tells The Associated Press that the service member allegedly shot Afghan civilians, but did not give details about the incident.

There are conflicting reports about how many people were wounded or killed.

In a statement, ISAF said the shooting will be investigated. It added:

"This is a deeply regrettable incident and we extend our thoughts and concerns to the families involved."

We'll be updating the blog with more information as it comes.

Update at 7:56 a.m. ET. New ISAF Statement:

In a new statement, the ISAF deputy commander, Lt. Gen. Adrian J. Bradshaw expresses his "profound regrets and dismay." Unlike an earlier statement, this one explicitly mentions reports of deaths:

"One of our soldiers is reported to have killed and injured a number of civilians in villages adjacent to his base. I cannot explain the motivation behind such callous acts, but they were in no way part of authorized ISAF military activity. An investigation is already underway and every effort will be made to establish the facts and hold anyone responsible to account."

Update at 7:40 a.m. ET. Reports On Death Toll:

While local officials have reported deaths, NATO has yet to confirm any. The number of dead varies from around 10 to more than 15. The New York Times reports at least 15 were killed, citing "local villagers and provincial officials." According to the BBC, 10 were killed and five wounded, though it says "the death toll could rise as high as 17."

Update at 6:08 a.m. ET. Unknown Motive, Reports Of Protest:

U.S. military spokesman Maj. Jason Waggnor tells The Washington Post they don't have information on the shooter's motive.

"He walked right off base, started shooting civilians, and returned to the base and turned himself in," Waggnor says.

The U.S. embassy in Kabul has issued a word of caution to residents and travelers in Kandahar province via Twitter, "due to reports of an on-going protest in Panjwa'i," the district where the shooting took place.

Update at 4:30 a.m. ET. Soldier Left Military Base:

NPR's Ahmad Shafi tells our Newscast Unit that, according to Afghan officials:

"A U.S. soldier opened fire on civilians after wandering off his military base in the Panjwai district of Kandahar province."

 

Update at 3:32 a.m. ET. Continued Tension:

Kandahar Gov. Tooryalai Wesa says people were killed and wounded in the shooting in Kandahar province, according to the AP. But NATO spokesman Capt. Justin Brockhoff said the coalition did not have reports of any deaths, but "multiple wounded."

As Al-Jazeera reports, "civilian casualties have been a major source of friction" between the Afghan government and U.S.-led NATO forces in the country. The news agency adds:

"Anti-American sentiment had already been running high before news of the latest civilian casualties."

Recent anti-American protests and violence in Afghanistan follow international forces' burning of Qurans, which were reported Feb. 21. U.S. officials, including President Obama, have apologized for the incident. The U.S. military says the religious texts were mistakenly mixed with trash.