A police officer and at least two civilians were killed during protests in the city of Goma in eastern Congo on Monday over worsening security, officials said.
Large rocks littered a street where crowds of demonstrators protested against regional violence and what they believe is the imminent arrival of security forces from neighbouring Rwanda to quell unrest.
The government denies Rwandan forces are coming to help.
Many in Goma are fed up with a surge in attacks by various armed groups in North Kivu and Ituri provinces that has led authorities to declare a state of siege, despite the presence of the army and a United Nations peacekeeping mission.
Congo has also launched a joint military operation with Uganda under which at least 1,700 Uganda troops have crossed into eastern Congo in recent weeks to battle the Allied Democratic Forces (ADF), a rebel group allied with Islamic State.