Indonesian police increased patrols Sunday in the tense province of Central Sulawesi a day after assailants beheaded three Christian schoolgirls.

A police official, Made Rai, said about 1,000 police officers, including reinforcements from other parts of the country, were securing the remote area of Poso where the girls were killed.

"So far no witness has been questioned and no suspect arrested," Rai said from Poso, about 900 miles northeast of Jakarta, the capital.

The bodies of the girls, dressed in brown school uniforms, were left at the site of the attack. Their heads were found at separate locations two hours later. One student survived the attack, which police said was carried out by six men wielding machetes.

President Susilo Bambang Yudhoyono described the killings as "sadist and inhuman crimes."

At the Vatican, Pope Benedict XVI offered his deepest sympathies to the families of the students.

Reports on the killings were featured across the front pages of nearly all Indonesian newspapers Sunday.

Media Indonesia, a leading daily, splashed a headline across its front page saying "Barbaric!" The Republika, another large newspaper, devoted its entire front page to the incident.

Central Sulawesi province has experienced bouts of sectarian violence over the years. About 2,000 people were killed in clashes between Muslims and Christians from 1998 through 2001, when a peace deal was reached. The worst violence abated after the deal, but there have been sporadic outbreaks since. Bombings in May in the Christian town of Tentena killed 22 people.

About 85 percent of Indonesia's 240 million people are Muslim. But in some eastern parts of the country, the Christian and Muslim populations are about equal.

Religious and communal tensions in many areas, including Poso, have been aggravated by a migration policy under which, for decades, large numbers of Muslims from Indonesia's most crowded areas moved to places that had been largely Christian.

In addition to religion, the newcomers often have cultural and language differences with locals. Politicians and security forces have sometimes been charged with exploiting the differences for their own ends, adding to the potential for violence.