Le Parisien newspaper reported that the well-maintained apartment block in the northern Paris suburb of Saint-Denis has been the scene of four different fires in the last week.
The attack happened after the woman opened her door to the men thinking they were alerting her about a new fire.
She was taken by helicopter to hospital after suffering third degree burns on around 40 percent of her body.
Neighbours reported hearing screams at around 3am on Sunday morning.
"I woke up at about 3 to feed my baby," said one neighbour. "Suddenly I heard someone shouting for help. At first I thought I was dreaming but the shouts continued. I went out and saw the smoke. My neighbour came out with a bucket of water. He went upstairs and threw it over the woman. Then he called the police."
In the last week a pushchair on a landing was set on fire, followed by a shopping trolley. Then pieces of material were set on fire and thrown threw the letterboxes of two apartments.
"This is a calm area that doesn't have these types of problem," said a spokeswoman for the local council. "We hope that the police can quickly catch the culprits before this gets worse."