Heavily armed gunmen have attacked the offices of the French satirical magazine Charlie Hebdo, killing 12 people.
Magazine editor Stephane Charbonnier and well-known cartoonists, as well as two police officers, a maintenance worker and a visitor, were among those killed, Associated Press reported.
According to eye witnesses, the masked gunmen opened fire with assault rifles in the office, which is located near Paris's Bastille monument, and exchanged gunfire with police in the street before fleeing in a car.
French Interior Minister Bernard Cazeneuve later confirmed that security services were hunting for three individuals.
One of the suspects, Hamyd Mourad, has reportedly surrendered to police, while the whereabouts of the others, Said and Cherif Kouachi, are still being traced.
Calling the attack 'an act of exceptional barbarism', French President Francois Hollande said: "We are at a very difficult moment.
"We are threatened because we are a country of freedom. We fight threats and we will punish the attackers."
Charlie Hebdo has repeatedly courted controversy with its satirical attacks on political and religious leaders of all faiths, and published caricatures depicting the Prophet Muhammad on its cover in 2011.
The weekly magazine also published a cartoon of the Islamic State head Abu Bakr al-Baghdadi.
No organisation has officially claimed responsibility for the attack, which is believed to be the deadliest terror attack on French soil since 1961.
However, a witness was quoted by the 20 Minutes daily newspaper as saying that one of the attackers shouted: "Tell the media that it is al-Qaeda in Yemen."
France has raised its terror alert system to the highest level and deployed additional soldiers to protect media offices, public places and other sensitive areas.
Image: French journalists, policemen and emergency services in the street outside the Charlie Hebdo offices a few hours after the attack. Photo: courtesy of Thierry Caro.