The outbreak of violence against Myanmar’s Rohingya Muslim minority has reportedly killed thousands more people than the government admits.

At least 9,000 Rohingya died in Myanmar from Aug. 25 to Sept. 24, Doctors Without Borders, also known as Médecins sans frontieres, said Thursday. That’s 22.5 times the official government estimate of 400 deaths.

Most of the deaths in that month-long period ― 6,700 ― were from violence, the group said, citing surveys it conducted with survivors in refugee resettlement camps in Bangladesh. The toll includes at least 730 children younger than 5. Causes include gunfire, arson and beatings.

Survivors have told aid workers of seeing dozens of Rohingya villagers beaten, sexually assaulted, stabbed, and summarily executed, and said entire villages have been burned to the ground.

Hala Sadak, 15, told Human Rights Watch last month that 10 soldiers dragged her from her home and raped her. “They left me where I was … when my brother and sister came to get me, I was lying there on the ground, they thought I was dead.”

Susana Vera / Reuters

Almost 650,000 people have fled Myanmar for Bangladesh since the end of August. MSF said its survey shows that the Rohingya people “have been targeted” by “clearance operations” launched by the Myanmar military, police, and local militias.

“What we uncovered was staggering, both in terms of the numbers of people who reported a family member died as a result of violence, and the horrific ways in which they said they were killed or severely injured,” Sidney Wong, MSF’s medical director, said in a statement. “The peak in deaths coincides with the launch of the latest ‘clearance operations’ by Myanmar security forces in the last week of August.”

Human rights groups and Secretary of State Rex Tillerson have called the death and destruction a campaign of ethnic cleansing.

Last month, Bangladesh and Myanmar entered discussions about a repatriation deal that would send Rohingyas back to the country’s Rakhine State. Meanwhile, Bangladeshi authorities are moving forward with plans to construct a new refugee camp, possibly anticipating more people fleeing extended conflict in Myanmar.