Postpublished at 12:51 Greenwich Mean Time 7 January 2015
"Everybody here at the White House are with the families of those who were killed or injured in this attack," spokesman Josh Earnest says.
Gunmen have attacked the offices of French magazine Charlie Hebdo in Paris, killing 12 people including the editor and celebrated cartoonists
The hunt is on for three suspects, named by police as Hamyd Mourad and brothers Said Kouachi and Cherif Kouachi.
It is the deadliest terror attack in France since 1961 during the Algerian war
President Hollande said it was an act of "extreme barbarity", with many foreign leaders also condemning the attack
In 2011, the satirical publication was firebombed after naming the Prophet Muhammad as its "editor-in-chief"
Mohamed Madi, Sherie Ryder, Julia Macfarlane, Alastair Beach and Victoria Park
"Everybody here at the White House are with the families of those who were killed or injured in this attack," spokesman Josh Earnest says.
European Union President Jean-Claude Juncker condemns the attack as intolerable and barbaric.
@CorkGourmetGuy tweets, external: Sickened and saddened by what has happened in Paris, no cause can justify murder, my thoughts are with all @Charlie_Hebdo_ #CharlieHebdo
Police officer stands in front of the offices of the French satirical newspaper Charlie Hebdo.
Charlie Hebdo was targeted for exercising its right to freedom of speech, journalist Douglas Murray tells the BBC. "I think that a lot about our future freedom of speech depends on whether or not people think that Charlie Hebdo brought this on itself or realise that the people who carried out this attack are solely to blame and must be the subject of vilification from everybody, from all faiths in all of our societies."
A Twitter campaign pledging support for the victims and the French magazine is gaining traction within moments of the first #JeSuisCharlie hashtag being posted.
The White House has condemned the attack
The attack took place in a busy part of Paris, not far from the centre and a passer-by tells the BBC: "The street's [often] used by drivers and Parisians to go from a place to another. The office is actually located in a place where a lot of people are going through."
More pictures have emerged from the scene.
The radical Islamic State group threatened to attack France minutes before Hebdo tweeted a satirical cartoon of the extremist group's leader giving New Year's wishes, AP says.
The masked gunmen who carried out Wednesday's attack committed France's deadliest terror attack in at least two decades, AP says.
French President Francois Hollande (second on the left) talks to the press upon his arrival at the headquarters of the French satirical newspaper Charlie Hebdo.
Two of the gunmen were dressed in typical jihadist "uniform" of black balaclavas, khaki ammunition pouches and were armed with Kalashnikovs, the BBC's Frank Gardner reports. They were heard shouting "Allahu Akbar".
The gunmen were armed with Kalashnikovs and a rocket-launcher, AFP reports.
The attack happened in central Paris, near some of the capital's most famous tourist attractions.
Gunmen who carried out the attack are still at large, French prosecutor says.
This is the latest edition of the magazine, showing controversial French novelist Michel Houellebecq.
Witnesses spoke of sustained gunfire at the Hebdo offices, the BBC's Hugh Schofield in Paris reports, as the attackers opened fire with assault rifles.
The 12 dead include two police officers, police say.
Twelve people have been killed in the attack, police say.