A gang has killed at least 26 people, including women and children, in an attack on three remote villages in Papua New Guinea. The assault, which took place earlier this month, involved “30 young men,” according to James Baugen, a police commander in East Sepik province. “It was a very terrible thing,” Baugen told the Australian broadcaster ABC. “Some of the bodies that were left overnight were taken by crocodiles into the swamp. We only saw the place where they were killed. There were severed heads.”

All the houses in the villages had been burned, and the remaining residents sought refuge at a police station, too frightened to name the perpetrators. Baugen added that the attackers were in hiding and no arrests had yet been made.

Volker Turk, the United Nations High Commissioner for Human Rights, confirmed the attacks that occurred on July 16 and 18, stating that they were motivated by “a dispute over land and usage rights.” Turk reported on Wednesday that the death toll could exceed 50 as authorities search for missing persons. Sixteen children were killed in the attack, and more than 200 villagers fled as their homes were set ablaze.

“I am horrified by the shocking brutality that has erupted in Papua New Guinea,” said the UN’s human rights chief, urging authorities to “conduct swift, neutral, and transparent investigations and ensure that those responsible are held accountable.”

Papua New Guinea, a country made up of hundreds of tribes and languages, has a long history of tribal violence. However, a rise in mercenaries and automatic weapons has intensified the cycle of violence. In recent decades, the country’s population has more than doubled, increasing pressure on land and resources and exacerbating deep tribal conflicts.

In February, Turk’s office urged the South Pacific nation to address the root causes of unrest after dozens were killed in a conflict between rival tribes. In February, at least 26 men were killed in an assault in Enga province. In May, eight people were killed, and 30 homes were set on fire in disputes in the same region.

Allan Bird, the governor of East Sepik, told ABC that violence in the country has worsened over the past 10 years. “In the last 10 years, if a crime is committed, investigations rarely lead to arrests,” he said. “Even if they are arrested, it is difficult to get to court and be imprisoned. This gives offenders more courage to do the wrong thing.”