CRI听力:Massive Manhunt for Paris Press Office Attack Gunmen

Police are now searching for two brothers from the Paris region and a man from the northeastern region of Reims in connection to the deadly shooting at the office of the French satirical newspaper Charlie Hebdo.

One of the brothers has reportedly been tried on terrorism charges.

Wednesday's shooting has so far left 12 dead, including eight journalists, the magazine's editor, and two policemen.

11 others were wounded, four of them seriously.

President Francois Hollande has called the attack a "cowardly murder" and has declared a day of national mourning.

"This shooting of extreme violence killed 12 people and injured several more. Greatly talented cartoonists, courageous journalists are dead. They left their mark on generations and generations of French through their influence, through their insolence, through their rare independence."

Hollande also noted that several terrorist attacks had been foiled in recent weeks in France.

Police say the heavily armed gunmen fled to northern Paris in a hijacked car after a firefight with police in the street following the shooting.

One witness says the gunmen, claiming to be with al-Qaida in Yemen, spoke fluent, unaccented French.

They were heard shouting "we have avenged the Prophet Muhammad" and "God is Great" in Arabic.

Interior Minister Bernard Cazeneuve says the security has been stepped up across France, with Paris placed the highest alert.

"I have asked the regional heads of police to take all the precaution measures needed at train stations and transport facilities, cultural institutions and a certain number of public institutions. We have increased the security deployment everywhere throughout the French territory with the mobilization of the national and local police, and of the military to ensure this protection."

Charlie Hebdo regularly satirizes religious and political figures and has sparked anger in the past among Muslims for publishing cartoons of the prophet Mohamed.