A man wearing an Afghan army uniform has killed three U.S. service members in southwestern Afghanistan.

NATO says the solders were killed early Friday in the Sangin district in Helmand province.

Afghan officials say the gunman was a police commander. They said he invited the soldiers to dinner, where he turned his weapon on them and fled.

The shooting is the latest in a series of killings and attacks in which foreign troops have been attacked by Afghan soldiers or insurgents disguised in their uniforms.

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.

So far this year, there have been at least 25 so-called “green-on-blue” attacks, a reference to the color of uniforms.

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