The knife-wielding inmate was holding four nurses and a guard.
The 37-year-old hostage, serving a sentence for rape, suffered from "significant mental problems." His sentence runs until 2031.
The prisoner has asked to be transferred to another prison, a person familiar with the case said, clarifying that "the situation remains calm".
Police forces, including the elite RAID unit, have arrived at the scene.
"We have mobilised all our resources," Justice Minister Gerald Darmanin wrote on X, adding that he was "monitoring developments in real time". | BGNES
