Roadside bombings and insurgent attacks killed 24 people in Afghanistan on Tuesday, including 13 police officers, officials said.

Nine of the officers were killed in a two-pronged attack by Taliban insurgents in southern Kandahar province just before dawn in Shorabak district, said provincial police chief Sayed Agha Saqib.

Insurgents first attacked a police checkpoint, killing five officers. Then they bombed two vehicles shuttling in police reinforcements to respond to the attack, Saqib said. Four officers were killed, and three wounded by the bombs.

Another roadside bomb in Logar province, south of Kabul, killed four police, said deputy police chief Abdul Majid Latifi.  

Militants regularly target the country's fledgling police force, which is seen as weaker than the better-trained and equipped Afghan army. At least 72 police officers were killed in insurgent ambushes and bombings in April alone.

The high death toll comes despite the fact that the U.S. has spent some $4 billion US to train and equip the police in the last three years.

Children killed as attacker rigs bomb

Elsewhere in Kandahar, a Taliban insurgent was planting a mine under a bridge in Daman district when it prematurely exploded, killing the insurgent and three children who were playing nearby, Saqib said.

In western Farah province, a bus hit a roadside bomb Tuesday, killing eight civilians and wounding another, said Farah deputy governor Younus Rasuli. All the casualties were men.

The western Afghan provinces, which border Iran, are frequently hit by insurgent attacks. Militants usually target military and police convoys, but civilians are often killed as well.

More than 1,200 people — mostly militants — have died in insurgency-related violence so far this year, according to a count by the Associated Press.