New York City fire officials say a deadly blaze that killed at least 12 people in a five-story Bronx apartment building Thursday spread through every floor of the building within a matter of minutes, the Associated Press reports. With a 1-year-old child among the victims and four others in critical condition, surviving residents described an inferno that left no time to escape. Two of those killed were reportedly found in a bathtub after the flames were put out. Fire Commissioner Daniel Nigro called the blaze “historic in its magnitude.” Investigators said that a gas line fueled the fire, but the initial spark is still under investigation. “It is an unspeakable tragedy, and families have been torn apart,” Mayor Bill de Blasio said. Sources cited by the New York Daily News said fire officials were looking into whether a space heater was to blame, though authorities say it’s too early in the investigation to make any conclusions. The fire is thought to be the deadliest one in New York City since 87 people were killed in a social-club fire in 1990.