KABUL: An American soldier walked off his base in southern Afghanistan and opened fire on civilians on Sunday, reportedly killing three, Western and Afghan officials said.

The soldier was held afterwards, NATO's International Security Assistance Force (ISAF) said in a statement.

"A United States service member was detained today in connection to an incident that resulted in Afghan casualties in Kandahar province," it said, without specifying the number of victims.

A Western official told AFP: "A soldier walks off the base (in the early hours of Sunday morning) and starts shooting. He got back to the office and was detained."

The governor of Kandahar province said three people were reportedly killed.

"Our initial information indicates that three people are dead but we don't know who they are," said governor Toryalai Wesa, adding that an investigation was under way.

The shooting comes after a series of incidents in which Afghan soldiers turned their weapons on American troops, killing six, after Korans were burned at a military base.

But there was no word on what might have motivated the soldier's actions.

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

"US Forces-Afghanistan (USFOR-A), in cooperation with Afghan authorities, will investigate this incident and release additional information as appropriate." -- AGENCIES