PARIS (AFP) - A massive manhunt was under way Tuesday in Paris, a day after a gunman shot and critically wounded a photographer at the offices of a major newspaper before opening fire outside a bank headquarters and hijacking a car.

Investigators have so far been unable to identify the gunman - described as white and aged between 35 and 45 - and branded a "real danger" by Interior Minister Manuel Valls.

A police source said Tuesday that about 400 calls had come in following an appeal for information from the public. "Of these 120 have been taken seriously and are being followed up," the source said.

Investigators issued a new photograph of the suspect taken by a close-circuit camera on Monday in Paris's central Concorde metro station, near the Avenue des Champs Elysees.

It shows a man with a round face, wearing a red jacket and a beige cap, and carrying a black shoulder bag. His motive remains unclear, but police believe the man was also behind an incident on Friday in which staff at a Paris news television station were threatened by a gun-wielding intruder.

The attacker, wearing a cap and wielding a 12-gauge shotgun, opened fire at the offices of left-wing newspaper Liberation at about 10:15 am Monday.

A photographer arriving for his first day of freelance work at the paper suffered buckshot wounds to the chest and stomach.

Liberation said he was 23, originally from the southern city of Toulon and had been about to work on a photo shoot on Christmas presents. He was taken to hospital in critical condition. The newspaper later said he underwent surgery and was being kept in intensive care.

Liberation's publisher Nicolas Demorand said on Tuesday the man was "still critical," although he was "in a slightly better state." "He was in a hopeless state yesterday when he was hospitalised," Mr Demorand said the shooting in the Liberation's entrance hall left staff traumatised but the paper vowed to carry on its work.