Afghan officials say an Afghan police commander has shot and killed three American special forces soldiers after inviting them to dinner at his checkpost in southern Afghanistan.

The U.S. military confirmed that a man wearing an Afghan army uniform killed the U.S. service members late Thursday in the Sangin district of Helmand province. Afghan authorities say the Afghan commander fled the scene after opening fire.

A Taliban spokesman said the attacker joined the insurgency after the attack.

It was the third time this week that international forces have been fired on by their apparent Afghan counterparts.

NATO troops killed an Afghan solider Thursday who tried to gun down coalition service members at a military base in eastern Afghanistan.

On Tuesday, NATO says two gunmen wearing Afghan National Army uniforms killed a coalition soldier in the east.

More than 33 coalition service members have been killed this year in so-called “green-on-blue” attacks. “Green on blue” is a reference to the color of Afghan and NATO uniforms.

Separately in southern Afghanistan, a NATO service member was killed in an insurgent attack Friday.

This week has been particularly deadly for international forces, with three coalition soldiers killed in a suicide attack on Wednesday in Kunar province. An Afghan civilian and a USAID Foreign Service officer were also killed in that blast.