The government had banned the demonstration and cut off all cell phone and internet access to hamper the rally against President Joseph Kabila who is clinging to power. Church groups had called for the rally.
Police shot and killed at least one anti-government protester in Kinshasa on Sunday during a banned protest that was organized by Catholic and evangelical churches against the extended rule of President Joseph Kabila.
"Since 7am we have received three injured people from the Catholic march. Two were seriously injured and one died from a bullet wound in the chest," said Dr. Francois Kajingulu of the St Joseph de Limete hospital in downtown Kinshasa.
Two more people were reported wounded in the northeastern city of Kisangani.
President Kabila has been in power since 2001, and his mandate expired in December 2016. In negotiations with the political opposition, Kabila was allowed to stay in power beyond his mandate on condition that elections be held by the end of 2017.
The government failed to organize a vote last year and now say an election is being planned for the end of 2018. But election officials have indicated that financial and logistical constraints could imperil that plan as well.
As Kabila clings to power many Congolese have grown to distrust the president.
"Our people no longer believe in the political will of our current leaders to ensure a peaceful transition of power," one of the main organizing groups wrote in a statement ahead of the march.
So far Kabila has refused to state clearly whether he intends to stand in the new election.
A dozen killed
Churches have become the main force opposing Kabila as political opposition parties have either been paralyzed by in-fighting or seen their leaders forced into exile.
Security forces have killed about a dozen protesters during two previous anti-Kabila demonstrations in recent months. The violent police crackdowns stoked fears that the country could be sliding into another conflict similar to that which led to the loss of some five million lives between 1994 and 2003.
On Saturday Kinshasa's police commissioner, General Sylvano Kasongo, announced a goal of "zero deaths" during the protests, when he held a review of his police force.
"It's our population, our countrymen that we are protecting," he said. "I told the policemen not to fire on the population, which is a civilian population that isn't armed."
Hundreds of ruling party supporters had stormed a Kinshasa cathedral on Saturday.
"We have come to take possession of Our Lady of the Congo Cathedral to take part in Sunday mass ... and defend the homeland," Papy Pungu, youth wing leader of the People's Party for Reconstruction and Democracy (PPRD), told AFP.
On Friday, the European Union, Switzerland and Canada issued a joint statement emphasizing the "importance of respecting fundamental rights including the right to demonstrate."
bik/jm (AFP, Reuters)