DAKAR, Senegal — Young girls and teens raped by Christian militia members. Mothers raped in front of their children by Muslim fighters. Women forced into sexual slavery by armed groups.

Rape and sexual slavery have been used as weapons of war by armed groups in Central African Republic for more than four years, with some of the attacks ordered or committed by commanders, Human Rights Watch said in a report Thursday.

More than 300 cases of rape and sexual slavery have been documented as carried out by members of armed groups in Central African Republic between early 2013 and mid-2017, the rights group said in their report. The sexual violence has come from members of the two main armed groups — the mostly Muslim ex-Seleka rebels and Christian anti-Balaka militia, said the report.

“Armed groups are using rape in a brutal, calculated way to punish and terrorize women and girls,” said Hillary Margolis, women’s rights researcher at Human Rights Watch. “Every day, survivors live with the devastating aftermath of rape, and the knowledge that their attackers are walking free, perhaps holding positions of power, and to date facing no consequences whatsoever.”

The report comes as hundreds of people have been killed since May and more than 500,000 people have been displaced as largely sectarian violence moves into parts of Central African Republic that were spared the worst fighting that began in 2013.

The sexual violence may constitute crimes against humanity but no member of an armed group has been arrested for the assaults, said Human Rights Watch. Only 11 of 296 survivors interviewed by the international watchdog said they tried to “initiate a criminal investigation,” and those who had informed authorities faced mistreatment, the group said. Relatives were killed, beaten or threatened in the cases of three women who confronted members of the armed groups over the rapes, the rights group said.

The newly established Special Criminal Court for Central African Republic must open as soon as possible to “help break the country’s entrenched impunity, but success will require sustained financial, logistical, and political support,” Human Rights Watch said. The U.N. mission in Central African Republic should help with investigations, said the report which also urged international donors and the government to provide medical, legal, mental health and socio-economic services for survivors of sexual violence.

The stigma of rape means the problem is under-reported, the group said. This compounds the trauma already experienced by survivors: Many have been raped in front of their children or other family members, some said they were held as sexual slaves for nearly 18 months and were often raped repeatedly by multiple men.

Many of those interviewed also said they suffered from physical injury and illness, including the transmission of HIV from the rapes, and some reported having suicidal thoughts, said Human Rights Watch.

The group’s researcher Margolis called for help for the women, and an end to impunity for the perpetrators: “There needs to be a strong and urgent message in the Central African Republic that rape as a weapon of war is intolerable, that rapists will be punished, and that survivors will get the support they desperately need.”