At least Seven people were killed and many others were injured during a stampede at a music concert in Congo’s capital Saturday, authorities said.

The stampede occurred at the 80,000-capacity Stade des Martyrs stadium in the heart of Kinshasa where Mike Kalambayi, a popular Congolese gospel singer, was performing, Kinshasa Gov. Daniel Bumba said.

State television RTNC said seven people were killed in the chaos and some of those injured were admitted to intensive care.

Authorities did not comment on what caused the stampede, saying an investigation into the incident was underway. However, the local music management company that organized the event said the chaos erupted when “the security services tried to neutralize some troublemakers.”

An estimated 30,000 people attended the concert, which featured several other musicians and pastors, the management company Maajabu Gospel said in a statement.

Videos that appeared to be from the scene and broadcast of the event showed large crowds gathered outside the stadium in front of barricades as they waited to enter. Inside, people could be seen rushing to the center stage.

Congo has witnessed such stampedes in past years, often blamed on poor crowd control measures such as excessive use of force. Eleven people died in a similar crush at the same stadium last October during a music concert.