A manhunt is continuing in Paris after a gunman attacked offices of the newspaper Liberation and fired outside the HQ of the Societe Generale bank.

A photographer, 27, was critically hurt at Liberation. The gunman later forced a motorist to drive him to the Champs Elysees before allowing him to go.

Police are looking for the same man who broke into the Paris offices of the 24-hour news channel BFMTV on Friday.

Police have now been stationed outside all the main media offices in Paris.

At a news conference, investigators held up two images, one of the suspect in a street and another taken from BFMTV surveillance cameras on Friday.

Paris prosecutor Francois Molins said the "most likely possibility" was that a lone gunman was behind the three attacks and the hijacking. He said the suspect had not yet been identified and the motive was still unclear.

The man is said to be between 35 and 45 years old, between 1.7m and 1.8m tall (5ft 6" and 5ft 10"), with stubble and greying hair.

Mr Molins said the suspect was wearing a black vest, a cap and white-soled green shoes.

The BBC's Christian Fraser in Paris says the gunman had walked into BFMTV on Friday morning and emptied the chamber of his gun in the reception area.

"Next time, I will not miss you," the man had said to an editor he threatened.

Our correspondent says that, for a time on Monday, a police helicopter hung over the Champs Elysees amid fears the gunman might be heading towards the Eiffel Tower, but it is speculated that he might have gone into the metro.

People were encouraged to stay indoors.

Police said the suspect was calm and assured, and each time has walked away from the scene of his attacks.

French media say the suspect told the motorist he hijacked that he was armed with grenades.

President Francois Hollande, who is in Israel, said the priority was "to stop an individual who had tried to kill and could try to kill again".

At 10:15 local time (09:15 GMT) on Monday, the gunman entered the Paris offices of Liberation, near the Place de la Republique in the east of the city, and opened fire.

He injured a photographer in the chest and stomach before escaping. Liberation said three spent cartridges had been found.

The gunman did not say anything during the attack, Liberation reported.

Some two hours later, the bank Societe Generale confirmed that a man opened fire outside its headquarters in the western business district of La Defense. No-one was injured, the bank said.

One witness of the bank shooting told Le Figaro that he heard a large bang and saw a man wearing a khaki coat and a cap and carrying a shotgun.

The gunman's second shot caused panic and the man then disappeared down some stairs on to a street, the witness said.

Another witness, Pierre-Albert Garcias, said: "We thought it was an explosion at first, it didn't sound like gunshots.

"I turned around and the man was in front of me, 10 metres away. He was actually reloading his gun. So we all ran for cover, we got down on our stomachs behind a wall."

Police say the gunman then hijacked a car in Nanterre, close to La Defense, and forced the driver to take him to the Champs Elysees, where he was dropped near the metro station George V.

Liberacion later said the photographer underwent surgery and was being kept in intensive care.

The victim - who has not been named - was said to be a freelance assistant photographer who had just arrived at the newspaper office to work on a fashion photo shoot.

Police sealed off the area around Liberation's offices. Interior Minister Manuel Valls has visited the scene, along with Culture Minister Aurelie Filippetti and the Mayor of Paris Bertrand Delanoe.

Mr Valls said: "As long as this person is still on the loose and we do not know the motives, this represents a threat. We must move fast."

Liberation's publisher Nicolas Demorand said: "In a democracy, when someone enters a newspaper office with a gun, this is very, very serious, whatever the person's mental state."

He added that the shooting had left the newspaper's staff traumatised.