Kabul, October 19 (RHC)-- Three U.S. nationals were wounded on Thursday in a shooting at the residence of the governor of Afghanistan's Kandahar province. Top U.S. commander in the country, Gen. Austin Scott Miller, was attending an event with other U.S. and Afghan officials at the governor's palace, but he was not injured, the Pentagon said.  One of the U.S. military's most valuable allies in the region was killed, however, along with two other Afghan officials.

"Initial reports indicate this was an Afghan-on-Afghan incident," Col. Knut Peters, a spokesman for the U.S.-led Resolute Support mission in Afghanistan said in the written statement.  "We can now confirm three Americans were wounded - one service member, one civilian and one contractor," Peters told CBS News. 

Kandahar's deputy provincial governor Agha Lala Dastageri said powerful provincial police chief Abdul Razik and the province's intelligence chief Abdul Mohmin died immediately in the attack and provincial governor Zalmay Wesa died of his injuries at a hospital.

The Taliban claimed responsibility for the attack and said Raziq was specifically targeted.  The Taliban claimed it was an "insider attack" -- one carried out by a sympathetic member of the Afghan security forces.  The militant group sent a photo to journalists of a young man in an Afghan border police uniform, whom it identified as the attacker. 

The attack in Kandahar came a day after a Taliban suicide bomber slammed into a NATO convoy near the capital city, Kabul, killing two civilians and injuring five Czech troops, Afghan officials and the Czech military said Thursday.

The attack on the NATO convoy came at the end of a particularly violent day across Afghanistan as tensions rise ahead of the country's parliamentary elections on Saturday.   A Taliban bombing in southern Helmand province killed a candidate running in the elections.  

In recent months, Afghan troops have come under near-daily attacks.  NATO troops, which handed over security to Afghan forces at the end of 2014, mostly train and assist with air power.  So far this year, eight U.S. soldiers and three other NATO service members have died in Afghanistan.

But with 14,000 American troops still serving in Afghanistan, D'Agata says it may still be too early to know what impact the new tactics are having.  Afghan military losses continue to be so high, that the government no longer releases the figures.