A 27-year-old man was left fighting for his life Monday after being shot by an intruder at the Paris offices of left-wing French daily Liberation.

The victim, a photographer's assistant, was shot in the chest and stomach with a pump-action shotgun and was in a critical condition, police and the newspaper said.

The shooter fled the scene and was still at large several hours after the attack, which occurred around 10:15am (0915 GMT).

Police were quickly deployed at major media offices in Paris for fear of further attacks.

The Liberation shooting came three days after a man stormed into the Paris headquarters of news channel BFMTV and emptied several cartridges from a similar shotgun before warning a senior editor: "Next time, I will not miss you."

Police are investigating a possible link between the two incidents.

Several hours after the shooting at Liberation, a number of shots were fired outside the headquarters of the Societe Generale bank in the La Defense business district on the western outskirts of Paris. No one was injured in that incident.

Liberation executive Nicolas Demorand said the shooting in the paper's entrance hall had left staff horrified.

"When you have someone with a shotgun coming into a newspaper's offices in a democracy, it is very, very serious, whatever the mental state of the person," Demorand told AFP.

"If papers and other media have to become bunkers, something has gone wrong in our society."

A police security cordon had been erected around Liberation's editorial offices in central Paris.

The newspaper said the injured man worked as an assistant to one of the photographers for Next, a supplement of the newspaper.

Liberation journalist Anastasia Vecrin described the horrifying scene she was confronted with on what was otherwise just a normal Monday morning.

"I was just arriving for work and I saw a man lying on the ground, holding his stomach and with blood everywhere," she told AFP.

"I met two of the reception staff who were completely white and who told me 'we've just been shot at'."

The shooting provoked a shocked reaction amongst French politicians. Interior Minister Manuel Valls announced that everything possible would be done to apprehend the shooter.

"This individual is on the run and he represents a real danger. We will do everything we can to arrest him," Valls said.