KAMPALA, Uganda (AP) — Hundreds of people have marched in the eastern Congo city of Beni to protest inaction against rebels who are suspected of killing at least 50 people in a weekend attack.

The head of a local rights organization, Jean Paul Ngahangondi, says police used live ammunition Wednesday to disperse the protesters and arrested several.

The killings in Rwangoma on Saturday led to street protests against the ongoing violence likely carried out by the armed group Allied Democratic Forces.

The group, with origins in neighboring Uganda, has been accused of killing more than 500 people in the region since October 2014.

The U.N. Security Council this week called on Congo’s government to take action to end the threats posed by the scores of armed groups destabilizing the region.