A surge in Afghan and coalition forces during the past two years routed Taliban fighters from many of their strongholds in the south, but the insurgents stepped up their attacks this summer to take back key areas.
The civilians, including women and children, were killed in a trio of blasts in Arghistan district, along Afghanistan's border with Pakistan.
Kandahar province spokesman Ahmad Jawed Faisal said one bomb exploded when a minivan ran over it Sunday morning. A second went off when other civilians riding a tractor arrived to help the wounded. A third explosion occurred about two hours later when a civilian vehicle hit a roadside bomb in another area of the district, killing two women.
At least 10 other civilians were injured in the three blasts.
According to the United Nations, last year was the deadliest on record for civilians in the Afghan war, with 3,021 killed. The number of Afghan civilians killed dropped 36 percent in the first four months of this year compared with last year, but the U.N. says that too many are still being caught up in violence.
The policemen were killed while responding to a gun battle being waged against insurgents early Sunday at a checkpoint in the Musa Qala district of neighboring Helmand province.
Daoud Ahmadi, the spokesman in Helmand, said a group of Taliban fighters attacked the police checkpoint at about 3 a.m.
Afghan police called for reinforcements, but on the way, one of the police vehicles hit a roadside bomb, killing the five policemen.
Ahmadi says three other policemen were wounded in the four-hour gun battle against the insurgents. He says the bodies of 20 insurgents were recovered from the battlefield.
Separately, two NATO service members were killed in southern Afghanistan—one in a roadside bomb explosion on Saturday and the other during an insurgent attack on Sunday.
NATO did not disclose where the incidents occurred, or provide the nationalities of the soldiers killed.
So far this year, 225 NATO service members have been killed in Afghanistan.