At least 11 people were killed and scores injured Thursday when explosions in the eastern Congo city of Bukavu struck a rally held by leaders of the M23 rebel group, which took control of the city earlier this month.

Rebel leaders blamed the bombing on the Democratic Republic of Congo's government and said attackers were among those killed in the blasts, with conflicting reports among rebels and local officials about the number of attackers and victims. Congo’s president blamed the attack on unspecified “foreign” forces.

“The attack caused 11 deaths and verifications are underway. The author of the attack is among the victims,” said Corneille Nangaa, leader of the Congo River Alliance, or AFC, which includes the M23. “There are 65 injured, six of whom are seriously injured and are currently being treated in the operating room.”

He told reporters that “following today’s unfortunate incident, we are obliged to react.”

Leaders of the M23 rebel group, including Nangaa, were meeting residents when the explosions occurred in the central part of Bukavu. Video and photos shared on social media showed a crowd fleeing the mass rally in Bukavu and bloodied bodies on the ground.

M23 accused the Congolese authorities of orchestrating the attack.

“We are accusing and condemning vigorously the criminal regime of Kinshasa, which … just implemented its plan of exterminating civilian populations,” AFC said in a statement. “This attack caused several deaths, including a few terrorists from Kinshasa and some injured. Two of them were immediately apprehended by our services.

“This cowardly and barbaric act will not be without consequences,” it said.

‘Change and development’

President Felix Tshisekedi called the attack “a heinous terrorist act that was perpetrated by a foreign army illegally present on Congolese soil.”

The rebels are supported by about 4,000 troops from neighboring Rwanda, according to U.N. experts, and at times have vowed to march as far as Congo’s capital, Kinshasa, over 1,600 kilometers away.

Jean Samy, deputy president of the civil society Forces Vives of South Kivu, told The Associated Press that the attack was “a sabotage.”

“Until now, we do not know where these grenades came from," he said by phone. “We have already recorded more than 13 deaths and serious injuries who will have to have their hands and legs amputated. The perpetrators of this act are still unknown.”

Nangaa was among leaders leaving the podium when two blasts rocked the scene, according to a journalist present at the rally. Nangaa had earlier told the rally that M23 was bringing “change and development” to their city.

Three-week offensive

Rwandan-backed M23 rebels have swept through the region seizing key cities and killing some 3,000 people in the most significant escalation of conflict in over a decade.

In a lightning three-week offensive, the M23 took control of eastern Congo’s main city, Goma, and seized the second-largest city, Bukavu.

The region is rich in gold and coltan, a key mineral for the production of capacitors used in most consumer electronics such as laptops and smartphones.

Rwanda has accused Congo of enlisting ethnic Hutu fighters responsible for the 1994 genocide in Rwanda of minority Tutsis and moderate Hutus.

M23 says it is fighting to protect Tutsis and Congolese of Rwandan origin from discrimination and wants to transform Congo from a failed state to a modern one. Analysts have called those pretexts for Rwanda’s involvement.