Protesters gathered outside the entrance to London's Downing Street on Wednesday to demonstrate in solidarity with people in Sudan.

It comes as Sudan's brutal two-year war entered a new, dangerous phase.

The paramilitary Rapid Support Forces this week seized control of the entire Darfur region, after ousting the rival Sudanese army from its last stronghold there.

The fighting for control of Sudan has killed over 40,000 people and created the world’s worst humanitarian crisis, with over 14 million displaced.

Protesters in London called for a boycott of the United Arab Emirates for allegedly backing the RSF, allegations the UAE denies.

They chanted "we demand a free Sudan" while waving Sudanese flags.

"It's very disheartening...the fact that I can't go back to my country, that I miss it with all my heart," said Ziyad Kashan who joined the protest.

The capture of el-Fasher, the provincial capital of North Darfur, by the powerful Arab-led force raises fears that Africa's third-largest nation may split again, nearly 15 years after the oil-rich South Sudan gained independence following years of civil war.

The RSF is led by Gen. Mohammed Hamdan Dagalo, a commander who had briefly ruled Sudan alongside his military rival, and whose meteoric rise to power has shaped Sudanese politics for the past decade.

Sudan's paramilitary forces killed hundreds of people at a hospital, including patients, after they seized the provincial capital of North Darfur, according to the U.N., displaced residents and aid workers.

The 460 patients and their companions were reportedly killed Tuesday at the Saudi Hospital by fighters from the RSF in the city of el-Fasher, said Tedros Adhanom Ghebreyesus, director general of the World Health Organization.

As part of their assault on el-Fasher, RSF fighters also went from house to house, beating and shooting at people, including women and children, witnesses told The Associated Press.

RSF commander Gen. Mohammed Hamdan Dagalo, who is sanctioned by the U.S., on Wednesday acknowledged what he called “abuses” by his forces.

In his first comments since the fall of el-Fasher, posted on the Telegram messaging app, he said an investigation was opened. He did not elaborate.

The Associated Press has not been able to independently confirm the hospital attack and death toll.

AP video shot by Kwiyeon Ha