The deaths of at least 6,700 Rohingya Muslims, including 730 children below the age of five, were caused by violence, a survey by humanitarian organisation Medecins Sans Frontieres found.

The organisation’s survey found that at least 9,000 Rohingya died in Myanmar between August 25 and September 24, and 71.7% of these deaths were caused by violence. The organisation said their findings were based on surveys of refugees in camps in Bangladesh, and called it “the clearest indication yet of the widespread violence” by Myanmar authorities.

According to the Myanmar government, the official figure of deaths is 400, BBC reported.

The organisation said gunshots were the cause of death in 69% of the violence-related deaths. Some 9% of the victims were burnt to death in their homes, and 5% were beaten to death.

More than 59% of the children killed during that period were shot, 15% burnt to death in their homes, 7% beaten to death and 2% died from landmine blasts.

The organisation said even these numbers were “the most conservative estimations”.

“The numbers of deaths are likely to be an underestimation as we have not surveyed all refugee settlements in Bangladesh and because the surveys don’t account for the families who never made it out of Myanmar,” said Dr Sidney Wong, Medical Director, Medecins Sans Frontieres. “We heard reports of entire families who perished after they were locked inside their homes, while they were set alight.”

The figure is the highest estimated toll yet of violence that erupted on August 25. The violence resulted in a massive refugee crisis. More than 6,47,000 Rohingya have since fled to Bangladesh, the organisation said.

Both the United Nations and and the United States have called the violence an “ethnic cleansing” of the Muslim minority, but have not released estimations of a toll so far.