NAIROBI, Kenya — At least eight people were killed and a dozen altar boys arrested in the Democratic Republic of Congo on Sunday after security forces cracked down on planned church protests against President Joseph Kabila’s refusal to leave office before coming elections.

Seven people were killed in Kinshasa, the capital, and one in Kananga, a city in the central part of the country, according to Florence Marchal, the spokeswoman for the United Nations Stabilization Mission in the Democratic Republic of Congo.

Congolese security forces set up checkpoints across Kinshasa, and the government issued an order to shut down text messaging and internet services indefinitely across the country for what it called “reasons of state security.”

Kinshasa, a city of 10 million people, had been militarized by the heavy presence of soldiers and the police, who sought to disrupt planned demonstrations, witnesses said.