Police said two men were injured in the shooting in front of the mosque of Bayonne, in southern France, on Monday afternoon.
They were rushed to Bayonne Hospital with gun shot wounds in the chest and arm, local media reported.
It is understood the victims are aged 84 and 87, French newspaper Sud Ouest said.
Four shots were fired and a car was set on fire outside the building at around 3.15pm.
A police spokesman said on Twitter: "Police intervention in progress at Rue Joseph Latxague in Bayonne. An individual arrested."
Radio station France Bleu reported the man arrested is in his 80s
More to follow...