An Afghan lawmaker contesting this week's parliamentary elections was among four people killed on Wednesday by a bomb planted under his office chair, officials said, in an attack claimed by Taliban militants.
Kandahar Governor Zalmay Wesa was also severely wounded on Thursday and contradictory reports whether he survived could not be confirmed early on Friday.
PM Khan also said that Pakistan suffered similar attacks during its own electoral process and could feel the pain of the people of the neighbouring country.
The shooting broke out in the compound of the governor of the embattled southern province of Kandahar, where the Taliban insurgency has been gaining ground.
The officials were fired upon after the talks when they were heading towards the helipad, local media reported, adding that the shots came from one of the nearby buildings.
Butler said the gunman had been killed and that Afghan officials were the "target of the violence".
The Taliban claimed responsibility for the attack.More news: Djokovic cruises past Coric to win fourth Shanghai title
A bodyguard for Kandahar's governor opened fire inside a building where senior officials had met to discuss the security situation in the south, Agha Lalay Datyagiri, Kandahar's deputy governor told Stars and Stripes. Gen. Harold J. Greene was killed and about a dozen USA soldiers were wounded when an Afghan soldier opened fire inside a building in Kabul.
The shootout left Kandahar police chief Brig. "We are being told the area is secure".
A Taliban spokesman, Qari Mohammad Yusuf Ahmadi, said in an email to journalists that the group carried out the attack and that its "main target" was Miller.
"Gen. Miller is unhurt", said Peters. Another 13 were wounded, including two Americans and the governor. Still, Mr. Mattis said he believed the attack would not affect Miller's security arrangements or the movement of the US military in Afghanistan. He too said all three officials were killed.
Afghanistan is tense ahead of the 20 October legislative election after the Taliban pledged to attack the ballot.
Now, the attack in Kandahar has diverted the attention of the country's security leadership to the province at a time when it is needed nationwide for the election.
The attack on the North Atlantic Treaty Organisation convoy came at the end of a particularly violent day across Afghanistan as tensions are rising ahead of the country's parliamentary elections on Saturday.
Eight US soldiers and three other North Atlantic Treaty Organisation service members have died in Afghanistan so far this year.