At least six people have died and several others injured in an explosion in Beni in the eastern Democratic Republic of Congo (DRC).The attack happened after a man reportedly let off a bomb at a Christmas celebration party.Under a state of siege since May, North Kivu province continues to suffer from insecurity and the explosion only added to the latest round of attacks by various armed groups operating in the area.Among the other 13 wounded and admitted to hospitals are two deputy mayors of the communes of Mulekera and Ruwenzori.Military officers have been running local administrations in eastern DRC since May in a bid by Kinshasa to tame the insecurity.According to the spokesperson for the military governor of North Kivu, Gen Sylvain Ekenge, the attack took place at 8 pm local time on Saturday, at the entrance to a busy bar in Ishango.He said the attacker activated the bomb at the entrance of the bar after being "prevented by security guards from entering the crowded bar," according to an official statement.A statement issued by President Félix Tshisekedi promised to pursue the criminals behind the attacks, saying “these crimes will not go unpunished and that the perpetrators will be hunted down and destroyed.”“The Head of State strongly condemns this heinous act. The Head of State salutes the memory of the victims and offers his condolences to the families of the victims,” it added on Sunday.This is the third bomb attack in Beni since June. The first targeted a Catholic parish in the Bustili neighbourhood, injuring two worshippers.The second took place in a drinking establishment, with the suicide bomber as the only victim. According to the spokesperson of the military governor, "the ADF (Allied Democratic Forces) terrorists, who are operationally desperate on the ground, have activated their sleeper cells in the town of Beni and the surrounding agglomerations with a view to taking action against peaceful citizens."Meanwhile, the Congolese and Ugandan militaries who have been running a joint operation against the ADF since November say they have intensified the offensive in eastern DRC.Read: Uganda shores up DRC base to hunt down ADF rebelsThe ADF, Ugandan rebels operating in eastern Congo, are also accused by Uganda of being responsible for recent attacks in Kampala last October and November.