Police say that Mourad was being held without charge after he reported to them after the incident and his peers say that he was in the same classes as them. It was reported that the young man recently graduated from a school in his home town of Charleville-Mézières.
A teenager who tweeted with the handle @babydroma said: "Please, he was in [school] all morning, he's in my class."
The hashtag #MouradHamydInnocent had been trending in France today while police launched a man hunt for the two other suspects. Helicopters and armed units have been patrolling northern parts of the country.
Cartoonists Stephane "Charb" Charbonnier, 47, Jean "Cabu" Cabut, 76, Bernard "Tignous" Verlhac, 57, Georges Wolinski, 80, and Philippe Honore, 73, were killed in the attack as well as magazine columnist and economist Bernard Maris, 68, and proof-reader Mustapha Ourrad.
Psychoanalyst and columnist Isa Cayat was the only woman killed in the shoot-out. Arts festival founder Michel Renaud and caretaker Frederic Boisseau were also murdered.
Two police officers, Ahmed Merabet, 42, and Franck Brinsolaro, 47, were also shot dead in the attack. Mr Brinsolaro was present in the editorial meeting that the gunmen stormed into as he was acting as Mr Charbonnier's bodyguard. Mr Merabet was killed while on patrol duty on the streets outside.
- Independent