Princess Martinez, 19, had gotten into a loud fight with her mother Saturday morning, neighbors told the New York Post. Martinez allegedly lit a mattress ablaze and bolted from the apartment with her mother still inside.
Building tenants said the fire spread quickly and many people panicked while trying to escape. One man said he thought it was a miracle no one was killed.
"You should have seen this place. People could have died, a lot of them,'' said the man, who declined to give his name. "I'm actually surprised that no one did because there were a lot of people inside at the time."
The building is in the University Heights section of the Bronx.
Six New York City firefighters were hospitalized for various injuries while fighting the fire, though none of the injuries were life-threatening, the department said.
Martinez is charged with arson and is being held in lieu of $100,000 bail.