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.

Congolese troops have fought back against Rwanda-backed rebels who the U.N. says are moving fast into the South Kivu province after seizing the region’s largest city and an international airport