The incident -- which occurred south-east of the provincial capital city, also called Kunduz -- took place Thursday evening in a region where German troops lead operations for the NATO-led International Security Assistance Force (ISAF), Defense Ministry spokesman Thomas Raabe said in Berlin.

Two civilian vehicles approaching the checkpoint failed to heed clear signals from the troops manning the checkpoint and the security forces then opened fire, Raabe said. Abdul Rahman Aqtash, security chief of the provincial police department, said the incident took place in Kharooti village, just outside Kunduz city.

Signals went unheeded

"When the vehicle did not stop after several signals, the German forces opened fire at the car," Aqtash said, adding, "When the forces later checked the vehicle, they found two children and a woman dead and four other children wounded in the vehicle."

German, Afghan National Army and Afghan police forces installed the checkpoint in the area after receiving information that a vehicle would smuggle drugs into neighboring Takhar province, he said.

"First, a vehicle approached the checkpoint but escaped when the forces tried to stop it," Aqtash said. "The forces opened fire at the second vehicle, which was driving behind the first one and did not heed repeated signals by the forces."

Injury and death toll rises

On Wednesday, a German soldier was killed in a roadside bombing in the Chardara district of Kunduz province. Three others were injured when a remote-controlled bomb blew up their armored vehicle.

More than 3,500 German soldiers are serving in the ISAF and are mostly stationed in northern provinces. The ISAF has about 53,000 soldiers from about 40 countries in Afghanistan.