In this May 30, 2013, file photo provided by the Murnaghan family, Sarah Murnaghan, center, celebrates the 100th day of her stay in Children's Hospital of Philadelphia with her father, Fran, left, and mother, Janet. The 10-year-old suburban Philadelphia girl received a lung transplant there Wednesday, June 12, 2013, her family said.

PHILADELPHIA - A 10-year-old girl whose efforts to qualify for an organ donation drew public debate over how organs are allocated was getting a double-lung transplant today after a match with an adult donor was made.

Sarah Murnaghan, who suffers from severe cystic fibrosis, was receiving her new lungs Wednesday at Children's Hospital of Philadelphia, family spokeswoman Maureen Garrity said. Murnaghan's relatives were "beyond excited" about the development but were "keeping in mind that someone had to lose a family member and they're very aware of that and very appreciative," Garrity said.

No other details about the donor are known, including whether they came through the regular donor system or through public appeals.

Murnaghan's health was deteriorating when a judge intervened last week, giving her a chance at the much larger list of organs from adult donors.

The Newtown Square, Pa., family received word about the donor lungs Tuesday night, Garrity said. The surgery began just after 11:30 a.m. and was expected to take at least six hours, she said.

Murnaghan's mother, Janet, said in a Facebook post that the family was "overwhelmed with emotions" and thanked all her supporters.

"Today is the start of Sarah's new beginning and new life!" she wrote, adding that the donor's family "has experienced a tremendous loss, may God grant them a peace that surpasses understanding."

During double lung transplants, surgeons must open up the patient's chest. Complications can include rejection of the new lung and infection.

Murnaghan's family and the family of another cystic fibrosis patient at the same hospital challenged existing transplant policy that made children under 12 wait for pediatric lungs to become available or be offered lungs donated by adults only after adolescents and adults on the waiting list had been considered. They said pediatric lungs are rarely donated.

On June 5, federal Judge Michael Baylson in Philadelphia ruled that Murnaghan and 11-year-old Javier Acosta of New York City should be eligible for adult lungs.

The Organ Procurement and Transplantation Network says 31 children under age 11 are on the waiting list for a lung transplant.

The network added Murnaghan to the adult waiting list after Baylson's ruling. Her transplant comes just two days before a hearing was scheduled on the family's request for a broader injunction.

Critics warn there could be a downside to having judges intervene in the organ transplant system's established procedures. Lung transplants are difficult procedures and some say child patients tend to have more trouble with them than adults.

The national organization that manages organ transplants this week resisted making emergency rule changes for children under 12 who are waiting on lungs but created a special appeal and review system to hear such cases.