HAT YAI — Suspected militants have detonated a roadside bomb that killed three police officers in Thailand's insurgency-plagued south.

Police Col. Anothai Jindamanee says the explosion went off Friday near a bridge in Rue So district in Narathiwat province as the officers were passing in a pickup truck.

He said the three policemen, including a deputy commander of the district police, were on their way back from attending a school activity.

The militants have mainly targeted security forces and teachers, who are seen as representatives of the government of the Buddhist-dominated nation.

More than 5,000 people have been killed in the three southernmost provinces since an Islamist insurgency erupted in 2004.