Paris. Police in Paris are on high alert after gun attacks at the newspaper Liberation and the bank Societe Generale.A photographer, 27, was seriously hurt and a motorist was briefly taken hostage not far from Societe Generale and forced to drive to the Champs Elysees before he was allowed to go.On Friday an armed man broke into the Paris offices of the 24-hour news channel BFMTV but fired no shots.Police have now been stationed outside all the main media offices in Paris.There has been no official confirmation that the same man is involved in all three incidents.A police helicopter is now hovering above the Champs Elysees, tracking the man suspected of shooting the Liberation photographer, says the BBC’s Christian Fraser in Paris.Police are encouraging people to stay inside.French media say the hostage-taker told the motorist he was armed with grenades.At 10:15 local time (09:15 GMT), a gunman entered the Paris offices of Liberation, near the Place de la Republique in the east of the city, and opened fire.He fired two shots from a hunting rifle, injuring a photographer in the chest and arm, before escaping.Eyewitnesses said he was aged about 40 and was wearing a cap and a raincoat. He did not say anything, 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.Liberation’s deputy editor Fabrice Tassel said the victim - who was shot in the chest - was fighting for his life.The man - 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 photoshoot.Police have 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.French President Francois Hollande asked Mr Valls to mobilise every means to stop whoever was responsible for the attacks and to shed light on the circumstances.