Guinea security forces killed three people on Thursday during a protest against President Alpha Conde, opposition and doctors said.
Doctors initially said police had shot dead one teen, but on Friday, the opposition and hospital sources said three people died.
The update brings to the protest death toll in the West African state to at least 20 since October 14. One gendarme has also been killed.
Guineans wearing the red colours of the opposition flooded Conakry's streets again Thursday after a call by the National Front for the Defense of the Constitution (FNDC), the alliance leading the protests.
Clashes erupted along the route of the march and spread to several neighborhoods.
The FNDC said Alpha Souleymane Diallo, Abdouramane Diallo, and 32-year-old Amadou Oury Barry, were killed by security forces during raids outside the area of the protest.
Another 66 people were injured, including 26 shot by police, Abdoulaye Oumou Sow, an FNDC leader told AFP.
All three deaths were confirmed by a medical source at the Sino-Guinean Friendship Hospital.
Guinean officials did not immediately comment on the updated toll, but had previously confirmed one death.
Police used water cannon and tear gas to break up the protests, and a bus was torched during clashes, images from the scene showed.
The security ministry said the police action came after the demonstrators threw stones at security forces.
The latest demonstration came a day after rights group Amnesty International gave a warning in respect to human rights and denounced "massive" and "arbitrary" arrests in the country.
The protests have been sparked by allegations that Conde is planning to change the constitution, scrapping constraints that prevent him from seeking a third term in office.