Roadside bombings and insurgent attacks Tuesday killed 24 people in Afghanistan, including 13 police officers, while U.S.-led coalition operations killed several militants, officials said.

In southern Kandahar province, Taliban insurgents killed nine police in a two-pronged attack before dawn in Shorabak district, said provincial police chief Sayed Agha Saqib.

Insurgents first attacked a police checkpoint, killing five officers, Saqib said. Two roadside bombs then hit two vehicles carrying police reinforcements, killing four more officers and wounding three.

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.

More than 900 policemen were among the 8,000 people killed last year. The high death toll comes despite some $4 billion spent by the U.S. to train and equip the police in the last three years.

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

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

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 Logar, protesters blocked a road after foreign troops killed a cleric during an operation before dawn Tuesday, local leaders said.

Abdul Hakim Sulaimankhel, chief of Logar's provincial council, said foreign troops raided a house and killed a cleric in Pul-e Alam district. Four suspects were arrested.

He said 300 protesters carried the cleric's body to a main road and blocked it. They demanded that the suspects be released.

The U.S.-led coalition said it was not involved in the operation, and NATO officials did not immediately have details of the incident.

U.S.-led coalition troops, meanwhile, killed "several militants" Tuesday during two separate operations targeting insurgents in eastern Paktia province and southern Helmand province.

The forces discovered and destroyed several weapons in Paktia and a cache of narcotics in Helmand.

U.S. Marines moved into Garmser late last month and have been battling militants in almost daily battles ever since.

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.