Kabul, Afghanistan (CNN) -- A suspected NATO airstrike killed eight civilians -- including six children -- in eastern Afghanistan, a provincial spokesman said.
The airstrike took place Saturday night in Paktia province, said Rohullah Samoon, spokesman for the governor of Paktia. He said an entire family was killed in the strike.
A large number of insurgents attacked NATO troops in the province, prompting them to return fire and ask for air support from a nearby base, said Maj. Martyn Crighton, a spokesman for the International Security Assistance Force.
The international coalition is aware of the reports that civilians died in an airstrike, Crighton said.
"We are taking any claim about civilian casualty very seriously, and we are looking at finding out information about what really happened last night," he said Sunday.
An investigation is in the early stages, and the international coalition is not taking or rejecting responsibility yet, Crighton said.
Samoon said the operation had not been coordinated with Afghan security forces. He said investigators have been sent to the area and will report their findings to President Hamid Karzai.
Karzai has assigned a delegation to investigate the incident, according to a statement from his office.
Separately, four ISAF service members were killed Saturday in southern Afghanistan, NATO said Sunday. The service members -- whose nationalities were not disclosed -- died after separate improvised explosive device attacks, the alliance said.