The sharpshooter was on a roof about a hundred metres away from a tent where Mr Hollande was inaugurating a new fast train line in the western town of Villognon.
A waiter and a train company employee were wounded, one in the leg and the other in the ankle, local media reports.
The safety on the marksman's rifle was reportedly off and the shot was fired while he was changing position, Sud-Ouest reported.
"I hope it is nothing serious," Mr Hollande said as his speech was interrupted by a loud gunshot. After looking to his left, he said "I don't think so" and continued.
Officials have launched a judicial investigation.
The two wounded people did not have life-threatening injuries, a prefect of police for the Charente region, Pierre N'Gahane, told BFM-TV.
Local media said Mr Hollande went to comfort the two wounded people after the shooting.
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