A shooting at a satirical newspaper in Paris has left 12 people dead, officials say. 

The Associated Press reports that masked men carrying automatic weapons rushed the office of the Charlie Hebdo weekly today, opening fire in the newsroom. SBP police union official Luc Poignant told the Associated Press that the assailants fled in a vehicle, which they later abandoned in favor of a stolen vehicle. 

French President Francois Hollande said the incident is "without a doubt" a terrorist attack, noting that other attacks have been prevented recently. According to the Associated Press, this is the deadliest act of terror to take place in France in nearly 20 years.

As the Associated Press explains, Charlie Hebdo previously faced threats for its depiction of figures like the Prophet Muhammad:  

The extremist Islamic State group has threatened to attack France and minutes before the attack Charlie Hebdo had tweeted a satirical cartoon of that extremist group's leader giving New Year's wishes. The cartoon entitled Still No Attacks in France had a caricature of an extremist fighter saying Just wait - we have until the end of January to present our New Year's wishes.

Charlie Hebdo has been repeatedly threatened for its caricatures of the Prophet Muhammad and other controversial sketches. Its offices were firebombed in 2011 after a spoof issue featuring a caricature of the prophet on its cover. Nearly a year later, the publication again published crude Muhammad caricatures, drawing denunciations from around the Muslim world.

The security level in France has been raised to the highest degree, and security at transportation hubs, media offices, retail stores, and places of worship have been heightened as well.

UPDATE: The Associated Press reports that an editor and a cartoonist are among the victims. France's top security official says three gunmen were responsible for the shooting, and that a manhunt is underway for the suspects.

UPDATE #2: MetroNews reports that the suspects are three men, ages 18, 32, and 34-years-old. The two older men, who were born in Paris, are reportedly brothers. 

The attack has triggered large-scale displays of support across France: 

BREAKING NEWS: More than 100,000 rally across France after Paris attack. Pic via @RomainSheller pic.twitter.com/SuNq5jSdiV

— Breaking News Feed (@PzFeed) January 7, 2015

UPDATE #3: The names of the three suspects have been released. According to the Associated Press, French officials have identified the older men as Said and Cherif Kouachi, while the 18-year-old has been identified as Hamyd Mourad.

[via Associated Press]