A one-year-old girl who was being held by her mother in a bathtub was the youngest victim to die in The Bronx apartment fire that killed 12 people and injured 15 more.

The mother of the child was also killed. The fire has been deemed the worst in New York City in 25 years. The cause of it is believed to have stemmed from a three-year-old boy who was playing with the gas burner on a stove inside of a first-floor apartment.

Fire Commissioner Daniel Nigro says that the boy had a history of playing with the burners and that his mother was not in the same room as him when the fire was started. His subsequent screaming alerted the mother, who then grabbed him and ran out of the apartment, leaving the door open.

Flames then spread quickly through the complex and shot up to the fifth floor of the building. Seven women and five men are among the dead, with victims aging between one and 63.

Names of those who perished have not been released by officials to the public yet, however family and friends have revealed that two-year-old Kylie and seven-year-old Kelesha Francis died along with their mother, 37-year-old Karen Francis, according to WNBC. 19-year-old Shawntay Young has also been identified as a victim.

The five-alarm fire, which broke out at the complex on the intersection of East 185th Street and Prospect Avenue, began a little before 7 p.m. Investigators believe a natural gas line may have helped fuel the flames. There were also reportedly six open building code violations, two of which were reported as recently as August.

A broken smoke detector and defective carbon monoxide detector were discovered in the same apartment on the first floor.

“I want to offer my prayers to all of the families who have lost their loved ones this evening,” NY Mayor Bill de Blasio said during a press conference this morning. “I ask all New Yorkers to keep them in your prayers.”

See video from de Blasio’s presser below.