One hundred and twenty-five women and girls were raped, whipped and clubbed in attacks so shocking that some aid workers in South Sudan say they are left speechless.

Doctors Without Borders says the “dramatic increase” in sexual violence occurred over 10 days as the women and girls walked to a food distribution site in Bentiu.

A midwife says those targeted include pregnant and elderly women and girls as young as 10.

Sexual violence has been widespread in South Sudan’s civil war.

The United Nations mission chief says the “abhorrent” attacks were carried out by young men in military uniforms and civilian clothing. The U.N. has increased patrols and launched an investigation while urging local authorities to hold the attackers accountable.

South Sudan’s government is not immediately available for comment.