Twelve people were killed and four more were seriously injured and fighting for their lives late Thursday in a fast-moving fire at an apartment building on a frigid night in the Bronx, according to New York City's mayor.

The victims included a child around a year old, Mayor Bill de Blasio said during a briefing outside the building.

"We may lose others as well," he said.

Fire Commissioner Daniel Nigro called the fire, "historic in its magnitude," because of the number of lives lost.

"Our hearts go out to every person who lost a loved one here and everyone who is fighting for their lives," he said.

The blaze broke out at a five-story building, a block from the grounds of the Bronx Zoo.

About 170 firefighters worked in bone-chilling cold, just 15 degrees, to rescue people from the building. Water sprayed from hoses froze into ice on the street.

The fire began on the first floor just before 7 p.m. and quickly ripped through much of the building, officials said.

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

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

Windows on some upper floors were smashed and blackened.

"The smoke was crazy, people screaming, 'Get out!," a witness, Jamal Flicker, told the New York Post. "I heard a woman yelling, 'We're trapped, help!"

According to city records, the building had no elevator. Fire escapes were visible on the facade of the building.

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