Fighters from the notorious paramilitary group Rapid Support Forces (RSF) ran riot in east-central Sudan in a multi-day attack that killed more than 120 people in one town, a doctors' group and the United Nations said.

It was the group's latest attack against the Sudanese military after suffering a series of setbacks, losing ground to the military in the area. The war, which has been ongoing for more than a year and a half, has wrecked the African country, displacing millions of its population and pushing it to the brink of a full-blown famine.

RSF fighters went on a rampage in villages and towns on the eastern and northern sides of the province of Gezira from Oct. 20 to 25, shooting at civilians and sexually attacking women and girls, the UN said in a statement on Saturday, adding that they looted private and public properties, including open markets.

The attack displaced more than 46,500 people in the city of Tamboul and other villages in eastern and northern Gezira last week, according to Sunday's data from the International Organization for Migration's Tracking Matrix.

"The killings and appalling human rights violations in Gezira province intensify the unacceptable human toll this conflict has taken on the people of Sudan," IOM director general Amy Pope told The Associated Press ahead of her trip to the country next week.

She called for concerted international efforts to stop the conflict, saying, "There is no time to lose. Millions of lives are in the balance."

"These are atrocious crimes," Clementine Nkweta-Salami, the UN's humanitarian co-ordinator in Sudan, said in a statement on Saturday. "Women, children and the most vulnerable are bearing the brunt of a conflict that has already taken far too many lives."

She said the attacks resembled the horrors committed during the Darfur genocide in the early 2000s, including rape, sexual violence and mass killings.

The RSF was born out of Arab militias, commonly known as Janjaweed, mobilized by ex-Sudanese president Omar al-Bashir against populations in Darfur that identify as Central or East African. At the time, the Janjaweed were accused of mass killings, rapes and other atrocities, and Darfur became synonymous with genocide. Janjaweed groups still aid the RSF.

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The Sudan Doctors' Union said in a statement that at least 124 people were killed and 200 others were wounded in the town of Sariha, adding that the group rounded up at least 150 others. It called on the UN Security Council to pressure the RSF to open "safe corridors" to enable aid groups to reach people in impacted villages.

"There is no way to help the injured or evacuate them for treatment," the statement said.

Footage circulating online, some shared by RSF fighters themselves, showed members of the paramilitary group abusing detained people. One video showed a man wearing a military uniform grabbing an elderly man by the chin and dragging him around as other armed men chanted in the background.

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Matthew Saltmarsh, a spokesperson for the UN refugee agency, says people who are trapped in war-torn Sudan are in an increasingly dire situation with no end to the conflict in sight.

The RSF didn't immediately respond to a request for comment.

The Co-ordination of Civil Democratic Forces, an alliance of pro-democracy parties and groups, also accused the RSF of storming villages and opening fire on civilians, as well as rounding up and mistreating "a large number of residents."

In a statement, the alliance held the RSF "responsible for these massive violations" and called for holding the preparators accountable.

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The attack on Gezira came as the military had successfully taken back areas held by the RSF.

In September, the military launched a massive operation in and around the capital, Khartoum, reclaiming large swaths of areas from the RSF. Also, earlier this month, it seized control of Jebel Moya, a strategic mountainous area in Gezira province, as well as areas in Gezira and nearby Sinnar province, driving out RSF forces.

In October, a top RSF commander, Abu Aqlah Keikel, the de facto ruler of Gezira, defected and surrendered himself to the military.

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That prompted RSF fighters to attack villages and towns in Gezira seen as loyal to Keikel, according to local reports.

The war in Sudan began in April 2023, when simmering tensions between the military and the RSF exploded into open fighting in Khartoum, before spreading across the country.

The war has been marked by atrocities such as mass rape and ethnically motivated killings. The UN and international rights groups say these acts amount to war crimes and crimes against humanity, particularly in the western region of Darfur, which has been facing a bitter onslaught by the RSF.

The conflict has killed more than 24,000 people so far, according to the Armed Conflict Location and Event Data, a group monitoring the conflict since it started.