A police officer was wounded in a shootout in southern Paris on Thursday, a police source told Reuters, adding that it was unclear at this stage whether there was any link to the killings at the Charlie Hebdo magazine.

Television station iTELE said two police officers were lying on the ground after the attack.

French police are carrying out manhunt for two brothers suspected of killing 12 people on Wednesday at satirical magazine Charlie Hebdo in Paris in a presumed Islamist militant strike.

On Thursday, authorities released photos of the two French nationals still at large, calling them "armed and dangerous."

Seven people have already been arrested in the ongoing investigation, Prime Minister Manuel Valls said.