At least 10 people were killed after the fire broke out in an apartment in central Paris in the middle of the night.
At least 37 people, including six firefighters, were injured, said Clement Coughnon, spokesman for the fire department. One person was seriously injured.
Remy Heitz said that a woman living in the building had been arrested and an investigation had been opened. Heitz said the 40-year-old woman was arrested on the road immediately after the fire. She has a history of psychological problems, he added.
"Firefighters continue to fight the fire on the two floors of the eight-story building and search for people," he told AFP, adding that the death toll could rise. He then said there was a risk of collapse between the upper floors.
The fire started at 1:00 pm local time on Tuesday (7:00 pm EDT) on Erlanger Street in the city's 16th district, and residents fleeing to the rooftops of neighboring homes.
Paris Mayor Anne Hidalgo and the Minister of the Interior, Christophe Castaner, visited the scene on Tuesday morning. Speaking to Heitz and Castaner at an impromptu press conference, Ms. Hidalgo said the building, which had at least 50 apartments, was very difficult for firefighters to access.
By 4:00 am local time, the building had been cleaned up, although some 200 firefighters remained on the scene to fight the fire. About 250 firefighters were mobilized during the operation, he said.