One woman is dead and dozens of people are displaced after a three-alarm fire in a large apartment building disrupted New Year’s morning in downtown Holyoke, authorities said.

The fire broke out at 106 North East St. in Holyoke’s Flats neighborhood shortly before 9 a.m., said Captain Anthony Cerruti, a Holyoke Fire Department spokesman.

Officials confirmed one fatality: a woman who Cerruti said had apparently jumped from either the fourth or fifth floor to escape the flames.

Investigators did not know Sunday whether all the other residents had escaped, but no one had been reported missing.

“There’s a lot of people in the building, and with the holiday and people being scattered about, we’re still chasing down the residents,’’ said State Fire Marshal Peter J. Ostroskey. “We’re not ruling anything out at this point.’’

Authorities have not named the victim, but Holyoke Mayor Alex Morse said that he spoke with the woman’s family Sunday, offering them hugs as they grapple with the loss.

“It’s absolutely heartbreaking to watch anyone in your community have to suffer or feel pain,’’ Morse said. “You want to be able to take that away from them.’’

Ostroskey said the authorities were in the very early stages of their investigation of the blaze, as firefighters continued to extinguish small flames that flared up in the smoldering structure.

He said that as firefighters worked to stabilize the building, part of it collapsed onto a smaller structure, apparently a two-family house, causing significant damage.

While officials still need to determine the value of the damage, “the building is a total loss,’’ Cerruti said.

The fire displaced at least 50 people, he said.

Morse said the owner of the building has 10 to 15 empty apartments that are available for the 25 displaced families, and that families for whom there is not an apartment will be placed in hotels.

He said area residents had made many donations of food, clothing, toiletries, blankets, and furniture for the displaced, and that city officials were working with the American Red Cross to support the families.

Additionally, the city has set up a GoFundMe page, with a goal of raising $100,000, Morse said. The page had raised more than $5,000 by Sunday evening.

The fire ran across the L-shaped 25-unitbuilding from the northeast side to another section that was separated by a wall, Cerruti said.

Cerruti said the fourth and fifth floors were engulfed in flames when firefighters arrived. Crews rescued at least five people who were waiting at windows on the upper floors, and several residents dropped children from windows, with people below using blankets as makeshift nets to catch them, Cerruti said. “It was a very chaotic scene,’’ he added. The fire left one firefighter with hand injuries.

Morse said witnesses told him that some children had to jump from windows and were caught by police.

“I couldn’t be more thankful to our firefighters and police officers,’’ he said, “for working so hard and so quickly to save as many lives as possible.’’

Jeremy C. Fox can be reached at jeremy.fox@globe.com. Mengqi Sun can be reached at mengqi.sun@globe.com.