BANDA ACEH, INDONESIA—Police in Indonesia’s most conservative province raided a punk-rock concert and detained 65 fans, buzzing off their spiky mohawks and stripping away body piercings because of the perceived threat to Islamic values.

Dog-collar necklaces and chains also were taken from the youths before they were thrown in pools of water for “spiritual” cleansing, local police chief Iskandar Hasan said Wednesday.

After replacing their “disgusting” clothes, he handed each a toothbrush and barked “use it.”