Soldiers killed one young person and wounded several other people in Conakry, witnesses and a doctor said Saturday, despite appeals for calm following days of political violence.
Three people have been killed and around 200 wounded since violence broke out in the Guinean capital on Wednesday at a demonstration by the opposition calling for transparency during May 12 legislative polls.
It was not immediately clear whether the latest incident was linked to the opposition protest.
A 15-year-old boy went to buy bread late Friday when soldiers "opened fire on him from point-blank range," a member of his family told AFP.
A witness and a doctor said 13 people were wounded, including one who died in a hospital.
Security forces "fired live rounds on well-targeted people who were not protesting in the neighbourhood" of Koloma, a witness said.
"They're continuing to fire live rounds on the population. I confirm that one of the young people wounded died this (Saturday) morning at the Mother and Children Clinic" in Conakry, doctor Abdoulaye Barry, who heads a medical centre in the suburb of Dixinn, told AFP.
It was the third death since mass opposition protests erupted Wednesday, which prompted both UN Secretary General Ban Ki-moon and Guinean President Alpha Conde to call for calm on Friday.
Violence broke out during a Guinean opposition demonstration in Conakry Wednesday, leaving some 130 people wounded including 68 police, Guinea's security minister said.
A student later died of his wounds, a hospital source said. Meanwhile, the government said a police officer died of wounds sustained in the protests.
"This violence not only led to the destruction of public and private property but also cost the lives of three fellow citizens: two civilians and a policeman," the government said in a statement.
A coalition of opposition parties on Saturday called for an end to actions by security forces that "endanger the lives and property of numerous citizens whose only crime is to have responded favourably to calls for an opposition protest," they said in a joint statement.
Thousands had gathered for Wednesday's demonstration to demand transparency in the upcoming election and protest against the South African company selected to revise the electoral roll.
The vote in the troubled West African country was due to have taken place in 2011 and has been postponed several times already.
On Thursday, clashes took place between security forces and young people in suburban neighbourhoods of the capital deemed favourable to the opposition.
On Friday, those selling mainly automobile spare parts clashed with food sellers.
The Guinean League for Human Rights on Saturday urged the government to "shed light on the serious human rights violations committed this week and bring the suspected perpetrators to justice to break the culture of impunity."