An Afghan police officer killed seven colleagues in central Afghanistan overnight, the third deadly insider attack in 24 hours.
The assailant fled after opening fire at a checkpoint in Tarinkot, the capital of Uruzgan province
The attack followed a shooting at a military training facility near Kabul that killed a U.S. general and injured about 15 others, including a German general.
In a third incident on Tuesday, an Afghan police guard died in gunfight with NATO troops in the eastern Paktia province.
In recent years, there have been dozens of instances in which Afghan forces turned their weapons on coalition forces, killing scores of troops from the U.S. and elsewhere and creating mistrust between the joint patrols.
The American major general, identified the officer as Major General Harold Greene, was the highest ranking U.S. official to be killed in Afghanistan in the 13-year conflict.
He was reportedly shot at close range by a gunman dressed in an Afghan military uniform during what a Pentagon spokesman called a "routine site visit" by senior officers to the Marshal Fahim National Defense University.
The insider attacks come as Afghanistan prepares for the withdrawal of foreign troops by the end of the year.