The Rwanda-backed rebels who captured a major city in eastern Congo have sought to reassure its residents about their safety.

Rwandan-backed M23 rebels captured the mining town of Nyabibwe in eastern Congo’s South Kivu province, violating a ceasefire they declared earlier this week, according to NBC News. The rebels now advance toward Bukavu, raising fears of further conflict after seizing the city of Goma last week.

The Rwanda-backed rebels who seized eastern Congo's key city of Goma announced a unilateral ceasefire in the region Monday for humanitarian reasons, following calls for a safe corridor for aid and hundreds of thousands of displaced people.

Officials and residents say Rwanda-backed rebels have gained ground in eastern Congo despite the unilateral ceasefire they declared earlier this week, taking control of a town 100 kilometers (60 miles) from the provincial capital of Bukavu.