12 Dead at French Magazine Attack.

At least 12 people were killed and four were seriously wounded in Wednesday's attack at the satirical newspaper Charlie Hebdo in Paris, French President Francois Hollande told reporters.

"This is a terrorist attack, there is no doubt about this," he said.

Two heavily armed men entered the Charlie Hebdo office in Paris's 11th District and opened fire inside, SPG police union spokesman Luc Poignant told CNN affiliate BFMTV.

He said the attack, close to Place de la Bastille, at least three police officers were injured. The Paris mayor's office said at least six people were wounded, according to BFMTV.

The French government raised the country's security alert system to its highest level Wednesday after the attack, according to French media.

Hollande and other senior government officials were due to arrive at the scene of the shooting.

A witness who works in the office opposite the magazine's told BFMTV that he saw two hooded men, dressed in black, enter the building with Kalashnikov submachine guns.

"We then heard them open fire inside, with many shots," he told the channel. "We were all evacuated to the roof. After several minutes, the men fled, after having continued firing in the middle of the street."

Witnesses also spoke of seeing a rocket launcher, according to French media reports.

It's not yet clear what happened to the gunmen or whether they remain at large. There has also been no claim of responsibility.

The satirical magazine's premises have been under long-running police surveillance because of a potential threat from Islamist extremists.

The magazine's office was burned three years ago in response to its publication of cartoons of the Prophet Mohammed.

In November 2011, Charlie Hebdo's offices caught fire the day it was due to publish a cover making fun of Islamic law.