Ten people including a baby have died in a fire at an eight-storey building in south-western Paris, officials say.
More than 30 people - including six firefighters - were injured. One person is in a serious condition.
Fifty people were evacuated by ladders from the blaze in the upmarket 16th arrondissement.
Investigators believe the fire - one of the most deadly in the French capital in years - was possibly started deliberately.
A woman detained earlier by police is no longer being questioned and, after undergoing medical and behavioural tests, has been admitted to the psychiatric infirmary of the Paris police, media reports quote the Paris prosecutor as saying.
Earlier, French President Emmanuel Macron said the country "had woken up to tragedy", and praised the fire services for their courage.
Rue Erlanger is a residential street close to the Parc des Princes football stadium and the Roland-Garros tennis venue.
How did people escape?
The fire started on the second floor and spread across the block - built in the 1970s, unlike many of the older, classic Parisian buildings nearby - shortly after 01:00 (00:00 GMT), forcing some residents to scramble on to nearby rooftops to escape the flames and smoke.
An eyewitness at the scene told French television:
"The fire alarm went off at 00:30, a little after midnight, and smoke was everywhere already. I live on the eighth floor, the top floor, so I tried to pass from balcony to balcony to get away, And then we huddled up in a corner. Other people climbed up to where I was to escape the flames."
About 250 firefighters were deployed to the scene, not far from the Bois de Boulogne park, helping to rescue those trapped on the roofs. Pictures showed flames coming from the top floor windows and firefighters in breathing apparatus scaling ladders to reach residents.
Rescue efforts were initially hampered by the fact that the apartments on fire were inside an inner courtyard with no vehicle access.
"When we arrived, we were faced with an apocalyptic situation. Lots of people were calling for help from the windows," a spokesman for the fire service said.
Firefighters said the building's courtyard had acted as a funnel, helping the flames to spread from the lower to the upper floors.
Six firefighters are among the injured, officials say.
The fire was brought under control after a five-hour operation.
Surrounding buildings in the area have been evacuated as a precaution. Town hall officials have been tasked with finding alternative accommodation.
On Tuesday afternoon, architects working for the Paris police assessed the building and said there was "a serious and imminent danger to the occupants", who are therefore barred from returning for now.
What were the circumstances surrounding the fire?
An investigation has been opened into the criminal charge of causing death by arson.
Several local residents said the fire had started after a dispute between neighbours in the block over loud music.
Paris Mayor Anne Hidalgo sent her condolences to the victims, and visited the site on Tuesday morning, along with Interior Minister Christophe Castaner.
Just a few weeks earlier, four people were killed after a huge blast at a bakery in the centre of the city.
At the scene of the tragedy
Hugh Schofield, BBC News Paris
This is a well-to-do apartment building in an affluent neighbourhood. Other recent, deadly fires in Paris have been in poor, overcrowded areas where safety norms have clearly being ignored.
By mid-morning, the fire had been extinguished and normal life was resuming. Sounds of children playing came from a schoolyard next door.
The building is on an inner courtyard, so from outside there was no sign at all of the anguish and the drama.
But groups of people were milling about, residents from neighbouring buildings who had been told to leave their homes. They wanted to know when they could go back.
The occasional witness arrived who saw it all: the screaming, the flames, the people on seventh-floor window ledges staring into the void.
They said they wouldn't ever forget.