Firefighters quickly extinguished the flames, the third deadly blaze in or near Paris in the past nine days, and most victims died as a result of inhaling smoke while trying to flee, officials said.
Police said a seriously injured victim had died hours later, bringing the death toll to 15.
A dozen injured were in an "extremely delicate situation," police said, suggesting that the death toll could rise further.
Patrick Seve, mayor of the town of L'Hay-les-Roses, near Orly airport, said the flames erupted at around 1 a.m.
Witnesses described the screams of panicked residents, some of whom leaped from windows as the blaze flared through the entrance hall. Dozens of fire vehicles and about 200 firefighters were mobilized.
The mayor said most of those who died had tried to flee the building through the entrance, where temperatures soared, while the residents who stayed inside their apartments were not injured.
"It was the people who rushed out who were met with temperatures of 300 degrees, smoke and asphyxiation," Seve said.
"That's what caused the catastrophic toll," he said, describing "a night of horror."
Witnesses claimed to have seen a group of youths who lived in the building start the fire, Seve said. Several people were taken in for questioning but were not necessarily considered suspects.
"Information provided by judicial police leads us to believe, with all the necessary caution, that youths from the neighborhood, the housing complex, even the building were involved," the mayor said.
As dozens of firefighters rushed to the scene, some youths, apparently angry about what they considered a slow response from rescue teams, had thrown rocks at them, Seve said. Rescue squads said they had responded in about 15 minutes.
"The firefighters were getting hit by stones while they were conducting heart massages," he said. Officials said at least five people were revived after suffering heart attacks, and one pregnant woman gave birth after being rescued.
Prime Minister Dominique de Villepin said in a statement that an investigation was under way into the fire "that could be of criminal origin."
Jean-Luc Marx, a local government spokesman, said the building had been built in the early 1970s as part of a state-supported plan for low-cost housing. It was recently renovated, he added.
Firefighters said the inferno, which blackened the lobby after breaking out near residents' mailboxes, swept into the stairwell and raced up at least three floors, damaging several apartments.
"There was smoke, and people were screaming and wanted to jump," said resident Claude Camps, 48, who fled with his wife. "When we came out there was nothing left in the entry hall."
Ground floor resident Florence Zadi said she and her husband had jumped from a window to safety after he opened their apartment door into a wall of smoke, and quickly shut it.
Authorities evacuated the 18-story building Sunday, and were preparing temporary lodging for the survivors. About 500 people were inside the building when the blaze erupted, officials said.
France already is grappling with how to deal with and prevent building fires after three other blazes in Paris since April that killed a total of 48 people, mostly African immigrants.
In response, the government announced a series of measures including the planned construction of new housing and the eviction of squatters from buildings considered dangerous.
Authorities are investigating possible arson in an Aug. 26 fire that killed 14 African children and three adults in a run-down apartment building. Three days later, another fire killed seven in a building used by squatters.
On Friday, authorities evacuated about 140 squatters from two dilapidated Paris apartment houses, with police moving in over the protests of screaming mothers and the sobs of children. The Interior Ministry has listed about 60 run-down buildings in Paris as possible targets for forced evacuation.
Thousands of people marched Saturday in Paris to demand better housing for the poor and condemn the eviction plans.