The gunman is still on the run, said Interior Minister Bernard Cazeneuve -- who rushed to the scene at Montrouge Sted Malakoff just south of the city -- contradicting information given earlier by a source close to the case, who said the suspect had been detained.
Police initially said the two victims were critical, but Cazeneuve said just the policewoman was fighting for her life.
The incident comes on a day of mourning in France after Islamist gunmen stormed the office of satirical magazine Charlie Hebdo on Wednesday, killing eight journalists, two police and two others.
The two brothers suspected of having gunned down the 12 people in the attack were spotted Thursday morning and are armed, sources close to the manhunt said.
The manager of a petrol station near Villers-Cotteret in the northern Aisne region "recognised the two men suspected of having participated in the attack against Charlie Hebdo", the source said.
There has so far been no claim of responsibility for the massacre that has deeply shocked France.
It is also being reported that several attacks have taken place against French mosques since the magazine killings.
AFP