Jakarta, Indonesia ? Unidentified assailants attacked a group of high school girls Saturday in Indonesia’s tense province of Central Sulawesi, beheading three and seriously wounding a fourth, police said.

The students from a private Christian high school were ambushed while walking through a cocoa plantation in Poso Kota subdistrict on their way to class, police Maj. Riky Naldo said. The rural area is close to the provincial capital of Poso, about 1,000 miles northeast of the Indonesian capital, Jakarta.

He said the heads of the three dead girls were found several miles from their bodies.

Indonesia is the world’s most populous Muslim nation. But Central Sulawesi has a roughly equal number of Muslims and Christians. The province on Sulawesi island was the scene of a bloody sectarian war in 2001-02 that killed about 1,000 people from both communities.

At the time, beheadings, burnings and other atrocities were common.

A government-mediated truce ended the conflict in early 2002 but since then, there have been a series of bomb attacks and assassinations targeting Christians. A market attack in the predominantly Christian town of Poso killed 22 people in May.