Story highlights No US troops were killed, the NATO-led mission says

The attack comes on the heels of another one targeting US troops

(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 wounded 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.

Initially, an Afghan military spokesman said four foreign soldiers were wounded when an Afghan soldier opened fire on foreign troops in Mazar-e Sharif. That spokesman did not identify the nationality of the injured soldiers.

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

Read More