Eight other security forces were also wounded in Monday night's attack in Shorabak district, Mohammad Yousof Younosi, a provincial council member in Kandahar, said.
An official from the provincial governor's office, who was not authorized to speak with the media, confirmed the attack and said there were casualties among the Afghan forces, but couldn't provide exact figures.
Qari Yusouf Ahmadi, a Taliban spokesman, claimed responsibility for the attack and said the group's fighters also seized weapons and ammunition.
Also on Tuesday, U.S. forces in Afghanistan revised the death toll from a Taliban attack a day earlier near the main American base in the country, saying three Marines were killed but not a contractor who was initially reported among the fatalities.
In northern Sari Pul province, at least five members of the country's security forces were killed when the Taliban attacked a joint army and police base, said Zabihullah Amani, the provincial governor's spokesman.
He said that seven other forces were wounded in Monday night's attack in Sangcharak district.
There was no immediate comment from the Taliban. Amani said four insurgents were also killed in the ensuing clashes.
In northern Samangan province, an Afghan army officer shot and killed two of his fellow soldiers and later fled to join the Taliban, said Sayed Hashim Bayan, the provincial police chief's spokesman.
He said the shooter seized a Humvee and some ammunition before making his getaway around noon on Monday.
The Taliban praised the soldier's actions and confirmed he joined their ranks in Dari Suf district.
Associated Press writer Lolita Baldor in Washington contributed.