Officials said four hostages from the supermarket siege were killed, and a further four people have been critically injured.
The two brothers - Cherif and Said Kouach - suspected of killing 12 people on Wednesday at the offices of French satire newspaper Charlie Hebdo had taken a hostage at a printing facility 40 kilometres northeast of Paris.
Gunfire and explosives rocked the town of Dammartin-en-Goële when heavily armed forces launched an assault shortly after 5 p.m. local time.
The hostage at this site has been reportedly freed unharmed.
Police simultaneously carried out a second raid at the supermarket near Porte de Vincennes on the eastern edge of the city, where four hostages and the gunman died.
Terrified hostages reportedly ran from the scene as the police launched the assault.
The hostage-taker in the supermarket was also suspected of fatally shooting a policewoman in southern Paris early Thursday and had connections to at least one of the brothers involved in the Charlie Hebdo attack.