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Matthew and Madonna Badger embrace as the casket of one of their three daughters arrives for funeral services on Thursday in New York City.

The mother of three young daughters who perished in a devastating Christmas morning blaze urged hundreds of mourners Thursday to commit "pure acts of kindness" in tribute to her children.

"I want to remember my girls out loud," Madonna Badger said, adding that the way to keep their memory alive was through love.

"My girls are in my heart," Madonna Badger told more than 500 mourners at St. Thomas Church in Manhattan. "They're right here. And that's where they live now."

Badger broke down several times as she described each girl in turn — Lily, 9, and 7-year-old twins Sarah and Grace — then wailed as she followed their coffins out of the cavernous Gothic church. She was accompanied by her estranged husband, Matthew Badger, and a friend, Michael Borcina.

Borcina was with Madonna Badger and her family when the lethal fire tore through her Connecticut home. He walked behind the grieving parents as the coffins were brought out of the church.

Badger's parents, Lomer and Pauline Johnson, also died in the fire.

More than 800 people crowded inside St. Thomas Episcopal Church for the service "in thanksgiving for the lives." Among those at the service were fashion designers Calvin Klein and Vera Wang, rocker Lou Reed, and actor Philip Seymour Hoffman. Madonna Badger is a fashion advertising executive who worked on Calvin Klein campaigns.

Authorities shut down three lanes of Fifth Avenue on the church's block in honor of the girls.

Badger said that she always used to wonder what a parent would do if her children died first. She said she couldn't imagine going on to live. "But here I am," she told the crowd.

She also said that her daughter Lily wondered how she would die, and that she'd told her daughter she didn't know because, "life is a mystery." And she said daughter Grace worried "a thousand times" that she would die before her mom.

Her mother reassured her that would never happen.

Singer-songwriter Rufus Wainwright performed a haunting a cappella version of "Over the Rainbow" during the service, which also featured hymns sung by St. Thomas' all-male choir.

Read complete coverage at NBCConnecticut.com

Santa Claus
St. Thomas Episcopal Church was less than a five-minute walk from the department store Saks Fifth Avenue, where the children's grandfather, Lomer Johnson, played Santa Claus in the days before the fire.

A private service was held later at Woodlawn Cemetery for the girls and their grandparents.

Badger and Borcina were the only survivors of the fire, which was attributed to a bag of smoldering ash and embers left in a first-floor mudroom.

Borcina is believed to have moved the ashes out of the fireplace because the girls wanted to make sure that Santa Claus could come through the chimney. 

All died of smoke inhalation. Lomer Johnson also suffered blunt head and neck trauma, which resulted from a fall or being hit by an object.      

One of the girls, found dead just inside a window, had been placed on a pile of books, apparently so Johnson could reach in and grab her after he jumped out. Instead, authorities say, he fell through the roof.      

Stamford police were helping fire officials investigate the blaze. Police said Monday officials want to know if there were smoke alarms, the status of renovation work in the house and whether the contractor had permits.      

The issue of permits could figure in the investigation because the Connecticut Department of Consumer Protection has said that neither Borcina nor his company, Tiberias Construction Inc., was registered to perform home improvement work in Connecticut.

A foundation has been developed in the girls' honor, called The Other 364 Foundation, "whose mission is to champion compassion every day of the year," according to a statement on badgerandwinters.com.

Checks may be made out to:

The Other 364 Foundation
c/o Badger & Winters Group
135 Fifth Avenue 3rd Floor
New York, NY 10010

Notes may be sent to love@badgerfamilysupport.com.

WNBC's Andrew Siff, NBCConnecticut.com and msnbc.com's Sevil Omer contributed to this report, as did The Associated Press.

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