A bullet's impact is seen on a window at the scene after a shooting at the Paris offices of Charlie Hebdo, a satirical newspaper on Jan. 7, 2015. Eleven people were killed and 10 injured in shooting at the Paris offices of the satirical weekly Charlie Hebdo, already the target of a firebombing in 2011 after publishing cartoons deriding Prophet Mohammad on its cover, police spokesman said. Five of the injured were in a critical condition, said the spokesman. Separately, the government said it was raising France's national security level to the highest notch. Reuters/Jacky Naegelen

Update as of 7:50 a.m. EST: The White House condemned in the "strongest possible terms" the attack on the headquarters of Charlie Hebdo in Paris.

“The United States stand ready to work closely with the French” to help them investigate the attack, White House spokesman Josh Earnest said, speaking on MSNBC, according to Agence France-Presse. “Senior officials at the White House have been in close touch with their counterparts in France this morning.”

Meanwhile, The Guardian reported that it was a press day at the magazine on Wednesday, because of which senior staff members of the magazine were present in the office.

Update as of 7:00 a.m. EST: The death toll in the attack on the offices of French satirical magazine Charlie Hebdo has risen to 12, according to reports. Ten journalists and two police officers are among the dead and five are critically hurt.

President François Hollande called the attack “an exceptional act of barbarism committed against a newspaper,” and that the French "need to show we are a united country.” According to Hollande, France has thwarted several terrorist plots in recent weeks.

“We will fight these threats and we will punish the attackers,” Hollande reportedly said.

Meanwhile, Rocco Contento, a police union spokesperson, said that the gunmen had stolen a vehicle after fleeing the building following the shooting, and were headed to the Porte de Pantin metro station with the police in pursuit, according to The Guardian. Four attackers reportedly hijacked one vehicle to get away after the attack and abandoned it later to switch to another vehicle, the report added.

Eleven people have been killed by at least two armed gunmen in a shooting at the Paris headquarters of French satirical magazine Charlie Hebdo on Wednesday, according to reports. A witness reportedly said he saw multiple masked men storm into the office.

At least 10 people were reportedly injured, five of whom were in critical condition. One journalist was among the casualties, while three police officers were among the injured, The Associated Press reported, citing a police union official. According to the Telegraph, the latest post on Twitter from the magazine was what looked like a cartoon of Abu Baghdadi, head of the Islamic State group. The headquarters of Charlie Hebdo was attacked in November 2011 after it put an image of the Prophet Muhammad on the magazine's cover.

"France is shocked by this terrorist attack," French President Francois Hollande reportedly said, adding that it was "undoubtedly" linked to terrorism. Hollande was on his way to the scene of the shooting. France is part of a U.S.-led coalition that's conducting airstrikes against ISIS in Iraq.

"About half an hour ago two black-hooded men entered the building with Kalashnikovs (guns)," Benoit Bringer told French TV channel iTELE. "A few minutes later we heard lots of shots."

The men were then seen fleeing the building, local media reports said.

"Several men in black cagoules were heard to shout 'the Prophet has been avenged,'" Pierre de Cossette, a broadcast journalist with Europe1 News, wrote, according to The Telegraph.

Police have warned other French media outlets to be on alert following the shooting, BBC reported. According to reports, France has raised its terror alert level in Paris and surrounding areas to its highest level after the attack.

Meanwhile, British Prime Minister David Cameron condemned the attack on Twitter.