Taliban has claimed responsibility for the incident.
On Monday, four USA soldiers suffered injuries as the troops convoy was struck by a car-bombing in the Dand district of Kandahar province.
At least 40 Taliban insurgents were killed and 35 others injured after they attacked security forces' check-posts in the Kandahar province.
A Taliban spokesman, Qari Yusuf Ahmadi, said that 13 Afghan police officers were killed in the Monday attack.
According to Kandahar police the attack started last night at about 8:00 pm and lasted for one hour.
The soldiers are in stable condition.
"The Taliban attacked the post and did not even give the police a chance to wake up and reach their weapons. the police were killed, still in their beds", a village elder told the Times. The attack on the U.S. military convoy in Kandahar added to the casualty toll.
The suicide bombers had planned to target the district council building and police headquarters using a Humvee vehicle, Durrani said.
The insurgents have carried out more complex attacks against security forces in 2017, with SIGAR describing troop casualties in the early part of the year as "shockingly high".
Casualties leapt by 35 percent in 2016, with 6,800 soldiers and police killed, according to U.S. watchdog SIGAR.
Earlier it was reported that North Atlantic Treaty Organisation next year will increase the size of its mission in Afghanistan from 13 to 16 thousand people.