There were 139 suspected graves discovered in a mountainous region along the Thai-Malaysia border in what authorities believe are abandoned jungle camps used by human traffickers. The graves are a gruesome reminder of the dire migrant crisis afflicting thousands in Southeast Asia.

“It is a very sad scene,” National Police Chief Khalid Abu Bakar told the Associated Press. “I am shocked. We never expected this kind of cruelty.”

The AP reports police found what they believe were human cages made from wood and barbed wire. “We think the migrants were imprisoned in these wooden pens,” Khalid told the AP. “They were not allowed to move freely and traffickers kept watch at sentry posts.”

Also found were a pink teddy bear and other children’s items, which led police to believe that children may have been held at one camp. Other items indicate that two of the camps may have been vacated only a few weeks ago.

According to the Guardian, residents of Wang Kelian knew something wasn’t right. Residents told the paper that weak and injured people would stumble into the town’s streets begging for food and water.

“They would walk into my shop, with injuries covering their hands and feet. Some were just too weak to even speak properly,” Lyza Ibrahim, who runs a food stall in the town on the northern Malaysian border with Thailand, told the Guardian.“One asked me, ‘[Is this] Malaysia?’ Then he pointed in the other direction, said ‘Thailand’ and shook his head to signal that he was not wanted there.”

Another resident, Mahyuddin Ahmad, who said he has given the migrants food and clothes, told the Guardian that he has seen migrants in Wang Kelian for the last two years but has seen more and more in the past month. “It is a common sight here. We didn’t suspect anything because we thought they just come from Thailand,” he said. “So we are really shocked to hear what the police revealed yesterday about the grave sites and jungle camps.”

The Associated Press reports that more than 3,600 people have landed on the shores of Indonesia, Malaysia and Thailand since May 10. Migrants from Bangladesh and Burma flee poverty and conflict, but thousands don’t make it. Some are left to die, trapped at sea. Others, such as those at the recently discovered camps, are held hostage, sometimes for months while traffickers extort more money from their families.

A similar discovery was made earlier this month in Thailand, where 36 bodies were found in seven abandoned camps, the Associated Press reported.