Four young demonstrators were killed in clashes between security forces and thousands of protesters in the Guinean capital Conakry on Monday, according to relatives and a doctor, as authorities said a gendarme had also been killed during the unrest.
The deaths occured during rallies called to oppose constitutional changes that could enable 81-year-old President Alpha Conde to seek a third term in office.
Pockets of violence erupted around the outer districts of Conakry, with some demonstrators setting up barricades, burning tires and throwing stones.
Hundreds of police and gendarmes responded with tear gas, stun grenades and real bullets, an AFP reporter saw.
The government confirmed only that a gendarme had been shot dead in the town of Mamou, east of the capital, adding that a resident in the city had been killed in unclear circumstances.
Tely Oury Bah, the father of one of the protesters, said his son Mamadou Lamarana Bah had been "coldly shot by a police officer".
"I cannot even go to see the body at the hospital mortuary because there is no way through, the roads are blocked", he said.
Earlier a local doctor said a 16-year-old boy had been killed and several others injured in the suburb of Sonfonia Gare.
The centre of the city, which hosts government offices and embassies, was under lockdown and almost deserted.
Calls for more protest
Residents and reporters in several other cities in the country reported disruption, with schools sending pupils home.
Interior Minister Bourema Conde said the protests were marked by acts "that threatened the lives of our citizens".
Several people were arrested and "the security forces are in control of the situation and calm reigns in the majority of the country", he said in a statement.
An alliance of unions, opposition parties and civil society groups called the National Front for the Defence of the Constitution (FNDC) had appealed for a massive turnout.
Police on Monday surrounded the house of the opposition leader Cellou Dalein Diallo and Sidya Toure, who heads the opposition Union of Republican Forces (UFR).
"I ask Guineans to continue to protest and to block the way until the power understands that you cannot impose a dictatorship on us by force," Toure told AFP by phone.
Alpha Conde is a former opposition figure who in 2010 became the West African state's first democratically-elected president, but his tenure has been marred by a crackdown on protests.
Last month he called on the public to prepare for a referendum and elections, stirring speculation that he is planning to overcome a constitutional bar on serving a third term. The next presidential ballot is due to be held late next year.
The opposition says about 100 people have been killed since 2010 when Conde took office. He won re-election five years later.