Nairobi, Kenya ? A wave of violence across the Kenyan capital killed 22 people early Friday, and police were investigating whether a shadowy gang that has threatened to launch an uprising against the government was involved.

Several of the attacks had the hallmarks of the Mungiki gang, which is accused in a string of beheadings and whose founder was sentenced to prison just hours before the violence erupted. Three of the victims were beheaded, and the Kariobangi neighborhood where at least eight people died is known to be an area where Mungiki operates.

Kiplimo Rugut, the commissioner of Central Province, said that Mungiki was suspected in some of the overnight killings. “This is a possibility we are looking at,” he told The Associated Press.

The violence comes at a tumultuous time in the Kenyan capital, where an explosion earlier this month killed one person and wounded more than 30 during rush hour. No one has claimed responsibility for the blast. In the past month, more than 50 people have been killed in a crime spree and police crackdown linked to Mungiki.

Mungiki claims to have thousands of adherents, all drawn from the Kikuyu, Kenya’s largest tribe. The group, whose name means “multitude” in the Kikuyu language, was inspired by the bloody Mau Mau rebellion of the 1950s against British colonial rule. In recent years, it has been linked to extortion, murder and political violence.

The group’s founder, Maina Njenga, who has publicly denied links to Mungiki recently but who is widely believed to still be a guiding force, was sentenced to five years in prison Thursday on gun and drug charges.

Meanwhile, a Mungiki leader said the government crackdown has done nothing to stop the secretive group, which makes money by demanding protection payments from minibus drivers and by controlling illegal businesses that produce homemade alcohol or provide electricity to slum areas by re-routing the circuits.

The minibuses, known as matatus, are the main form of public transportation in Kenya.

“Nothing has changed,” the leader said, insisting his name not be published because he is wanted by police. “Most politicians in this area are affiliated with us in one way or another.”

He spoke the day before Friday’s violence, and could not be reached for further comment.

A senior police officer, who also requested anonymity due to the sensitivity of the matter, said corruption is the main reason authorities cannot stamp out the Mungiki.

He said officers round people up, then take bribes to release them. “The officers also tip members of the group to an impending raid,” he said. “If we wanted to eradicate Mungiki we could do it in a day.”

Simon Kimutai, head of the Matatu Owners Association, said the Mungiki have become so threatening that he is forced to work from his car so gangsters won’t find him at his office.

“I am talking about (the Mungiki) every day and nothing is happening, so what will happen next is that they will come for my head,” he said.