The killers, reported by eyewitnesses to be masked gunmen armed with Kalashnikovs, escaped after a shootout in the street with police.
Speaking to Sky News, Henry Samuel, the Daily Telegraph’s Paris correspondent, said: “According to people on the ground, two masked gunmen burst into the offices very heavily armed, (with) Kalashnikovs, apparently even with a rocket-propelled grenade, and opened fire, leaving several minutes later.
“Somebody who was nearby on the roof and saw much of the incident said three policemen then arrived on a pushbike. When they saw how armed these men were they left and then there was a kind of gunfight in the street.”
French President Francois Hollande has confirmed that the security level in Paris has been raised, as the hunt continues for the gunmen.
Prime Minister David Cameron tweeted his support to the people of France.
The murders in Paris are sickening. We stand with the French people in the fight against terror and defending the freedom of the press.