LOUISVILLE, Ky. (FOX) -- At least 12 people were killed and others injured after a massive fire broke out in a New York City apartment building, Mayor Bill de Blasio said at a press conference Thursday night.

"Tonight here in the Bronx, families have been torn apart," de Blasio told reporters. The mayor called the event the "worst fire tragedy we have seen in this city."

More than 160 firefighters were on the scene of the four-alarm fire, located at a five-story walk-up apartment house in the Bronx, just a block from the borough's famed zoo.

Officials said that one baby died in the fire, which FDNY Commissioner Daniel Niger called "historic in its magnitude." Four people are critically injured and others are also seriously injured. The victims range from 1 to 50 years old.

New York Gov. Andrew Cuomo tweeted: "We are closely monitoring the devastating fire in the Bronx. As always we are thankful for our first responders. Our thoughts are with the victims and their families tonight.

The fire, which is now under control, broke out just before to 7 p.m. Thursday night. Temperatures are in the mid-teens in New York, with winds making it feel like single digits.

The building had no elevator, The Associated Press reported, citing city records. Fire escapes were visible on the facade of the building.

The fire started on the first floor of the building before it spread, officials said. The fire department responded to emergency calls within three minutes.

The commissioner added it's too early to determine what sparked the fire.

One witness, Xanral Collins, told the New York Post he saw a father running toward the building, but was unable to enter.

"I saw him screaming, 'My babies are dead! My babies are dead!'" Collins said.

Neighborhood resident Robert Gonzalez, who has a friend who lives in the building, told The Associated Press she got out on a fire escape as another resident fled with five children.

"When I got here, she was crying," Gonzalez said.

De Blasio, at Thursday's press conference, advised to "Hold your families close and keep these families here in the Bronx in your prayers."

One of the deadliest fires in recent memory happened elsewhere in the Bronx in 2007. Nine children and one adult died in a blaze sparked by a space heater.

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