(CNN) -- Army troops and rebels clashed on Wednesday in the violence-ridden eastern part of Congo, threatening to undermine an already fragile stability.

Hundreds of people in North Kivu fled toward the city of Goma by road trying to escape the fighting. The sound of heavy artillery echoed through the hills. The Congolese army continued a second day offensive to recover the cities of Rugari and Rumangavo, and to takeover these positions held by the insurgency.

"The situation is deteriorating because of the fighting between various groups," said Ronald Paul Veilleux, the International Rescue Committee's provincial director for North and South Kivu.

As of January 2009, an estimated 1.5 million people in North and South Kivu provinces have been internally displaced, and the number continues to rise, according to the United Nations.