Barack Obama condemns Paris magazine office attack

"I strongly condemn the horrific shooting at the offices of Charlie Hebdo magazine in Paris," Obama said in a statement.

"Our thoughts and prayers are with the victims of this terrorist attack and the people of France at this difficult time. France is America’s oldest ally, and has stood shoulder to shoulder with the United States in the fight against terrorists who threaten our shared security and the world. Time and again, the French people have stood up for the universal values that generations of our people have defended," the US President said.

He has also assured France of all assistance to combat with the "terrorists."

"France, and the great city of Paris where this outrageous attack took place, offer the world a timeless example that will endure well beyond the hateful vision of these killers. We are in touch with French officials and I have directed my Administration to provide any assistance needed to help bring these terrorists to justice," he said.

Unknown gunmen on Wednesday opened fire and shot down at least 12 people in Paris office of French satirical magazine Charlie Hebdo.

The attack left about 20 people injured.

Four senior cartoonists including Editor-in-chief Stephane Charbonnier were killed in the attack.

French President Francois Hollande said the incident was “undoubtedly a terrorist attack."

"Several terrorist attacks were thwarted in recent weeks," he was quoted as saying by france24.com.

"No barbaric act will ever extinguish the freedom of the press. We are a united country that will react and do block," he told mediapersons.

The attackers fled the building and could not be traced yet.

France raised its security alert to the highest level and reinforced security at places of worship, shops, media offices, and transportation, said reports.

Charlie Hebdo is a French satirical weekly newspaper, featuring cartoons, reports, polemics and jokes.

It had earlier courted controversy with its take on news and current affairs.