Three teenage girls are said to have confessed to starting a fire which engulfed an apartment block in a Paris suburb at the weekend, killing 16.
The fire raged through the lobby and engulfed several floors
It was the third fatal blaze in the Paris area in nine days.
According to police, the girls - two aged 18, the other 16 - said they had set fire to letter boxes in the 18-storey building for fun.
The latest fire was in L'Hay-les-Roses, near Orly airport. The previous fatal fires were in central Paris.
The death toll climbed to 16 overnight, when a young man suffering from smoke inhalation died in hospital. Three of the dead were children.
The apartment building was not used to house immigrants, unlike those engulfed by fire last month.
The blaze was quickly put out by some 160 firefighters, but people were mainly killed by the fumes, according to officials.
Police said two of the girls they questioned lived in the high-rise building, which housed 110 apartments.
It was built in the 1970s, but had been recently renovated.
The blaze came only a few hours after thousands of people marched through Paris in protest at the two previous fires nearer the city centre, which killed many African immigrants.
The protesters demanded better housing.
The French authorities have been criticised for housing poor immigrants in inadequate accommodation.
The march began at the site of the first fire in Paris' 13th district, in which 14 children and three adults died on 26 August.
Seven people died in a similar blaze in a dilapidated building four days later.
Sunday's fire was the fourth in less than five months in the Paris area.
In April, 21 people died when a fire destroyed a budget hotel in the centre of the city.
RECENT DEADLY PARIS FIRES
1. 15 April: Blaze at Paris-Opera hotel kills 24
2. 26 August: Fire in 13th district kills 17, including 14 children
3. 30 August: Seven die in Marais fire, including four children
4. 4 September: 16 die in L'Hay-les-Roses suburb