Officials have said that four people died and 10 were injured on Tuesday during protests in the Republic of Congo.
Clashes intensified after the government of Congo banned a demonstration against next Sunday’s referendum on President Denis Sassou Nguesso's proposal to extend his three decades in office.
The demonstrators gathered in some central neighborhoods in defiance of a government ban on public meetings announced on Monday.
The Protestors waved banners reading "Sassou get out" and "No to the referendum."
"People are demonstrating across the city. The police are firing tear gas bombs," said Tresor Nzila, executive director of Congolese Observatory of Human Rights. "In certain places, the police have fired warning shots with live fire."
"In order to allow the electoral campaign to continue without injury or provocation, the government has decided to forbid the use of certain meeting spaces," Raymond Zephyrin Mboulou, the Congolese communication minister said.
Interior Minister Raymond Mboulou told state TV that an "organised and coordinated insurrection" caused three deaths in Congo's capital Brazzaville and a fourth in the southern town of Pointe-Noire.
"The symbols of the republic, such as the police headquarters (or) gendarmerie brigades, were targeted," he said.
"The United States strongly urges all parties, including both the government and the opposition, to engage in dialogue and to refrain from violent actions that would undermine the hard-won peace that all citizens deserve," Sarah Sewall, the under-secretary of state for civilian security, democracy and human rights, said at a press conference in Kinshasa.
The human rights group Amnesty International published a statement urging security forces not to use excessive force against demonstrators.
Denis Sassou was first elected in 1979 and served as president until 1992. However, he returned to power in 1997.