Afghan officials say at least 11 civilians and 13 policemen have been killed in violence in three different provinces of Afghanistan.

In southern Kandahar province, police say Taliban insurgents killed nine policemen Tuesday in a two-pronged attack in the remote Shorabak district. Militants first opened fire on a police checkpoint, then targeted police reinforcements responding to the incident.

Also in Kandahar, three children were killed when a bomb being planted under a bridge exploded prematurely. Afghan provincial officials say the militant planting the bomb was also killed by the blast.

In western Farah province, eight civilians were killed when a bomb blast hit their bus in the Delaram district.

And officials say four Afghan policemen were killed in Logar province, south of Kabul, when a roadside bomb hit their vehicle.

Also in Logar, hundreds of protesters blocked a highway after foreign troops killed a religious teacher in an overnight raid.

In the southern province of Helmand, U.S.-led forces say they killed several militants during an operation to stop weapons smugglers in Garmser district.

Tens of thousands of foreign forces have been helping Afghan soldiers battle insurgents and rebuild Afghanistan since the U.S.-led coalition pushed the Taliban government from power in 2001.

Some information for this report was provided by AFP, AP and Reuters.