By Jay Croft

CNN

(CNN) -- Seven US military service members were wounded Saturday in an insider attack at Camp Shaheen in northern Afghanistan, the NATO-led Resolute Support Mission said.

The injured troops have been evacuated for treatment, the mission said in a statement. No US troops were killed.

The attack appears to have been a "green-on-blue" act by an Afghan soldier, a coalition official told CNN.

Four foreign soldiers were also injured when the Afghan soldier opened fire on foreign troops in Mazar-i Sharif, an Afghan military spokesman told CNN. The nationality of the other injured soldiers was not immediately known.

The NATO-led mission said it has opened an investigation.

Afghanistan's Ministry of Defense also is investigating, said Abdul Qhahar Aram, head of strategic communication and public affairs for the 209 Shahin Corps.

A massive attack in April on the same Shaheen base by Taliban militants left scores of Afghan soldiers dead.

Earlier this week, a convoy carrying US and Afghan forces was struck by a roadside bomb and came under small arms fire. The convoy returned fire in self-defense, and there were no US casualties, NATO said in a statement.

Last Saturday, three US soldiers were killed and another was wounded during a joint US-Afghan military operation in Afghanistan's Achin district. The Taliban claimed responsibility for that attack.

CNN's Barbara Starr and Ehsan Popalzai contributed to this report.

The-CNN-Wire

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