Gunmen lobbed a grenade and sprayed a police checkpoint with gunfire in southern Afghanistan, killing eight officers, a police chief said Friday.

The attack in Kandahar's Panjwayi district late Thursday also left one officer wounded and two others missing, said provincial police chief Sumanwal Matiullah.

The area where the attack occurred is known as a base for Taliban militants.

Police in Afghanistan are frequent targets of Taliban attacks. The under-trained and under-resourced force lost more than 1,000 officers in Taliban attacks last year.

Overall, more than 8,000 people were killed in insurgency-related attacks in Afghanistan last year — the most since the 2001 U.S.-led invasion. Violence has claimed more than 2,100 lives so far this year.

Elsewhere, a roadside blast next to a police vehicle in central Ghazni province killed two officers and wounded five others, said deputy provincial police chief Mohammad Zaman. He blamed Taliban militants for the attack.

Meanwhile, in eastern Paktika province, Afghan and foreign troops killed seven suspected militants during a clash near the Pakistan border, said Ghamai Mohammadyar, a spokesman for the provincial governor.

The militants had crossed from Pakistan and attacked Afghan border guards in Bermal district, he said. There were no casualties among Afghan and foreign troops.

Afghan and Western officials say Taliban and other militants regularly use Pakistan's lawless tribal areas as bases for launching attacks against Afghan and foreign troops in the country.

The number of militant attacks have been on the rise this summer, compared with the same period last year, NATO officials say.