Cancer-Stricken Teen Serenades Pope Francis With Moving A Capella Version of 'Ave Maria

After kicking off his first trip to Mexico over the weekend, Pope Francis visited the Federico Gomez Pediatric Hospital in Mexico City on Sunday, where he received a surprise serenade from a cancer-stricken teenager being treated at the facility.

The pontiff is seen in a video of the encounter standing over the young woman, as he intently watches her beautifully belt out an a capella version of "Ave Maria."

When she finishes, he smiles and bends down to give her a hug — a touching moment that has captured a fair bit of attention.

Pope Francis waves to well-wishers upon arrival from Sri Lanka, Thursday, Jan. 15, 2015 at suburban Pasay city, south of Manila, Philippines. (AP/Bullit Marquez)

The Catholic News Agency called it "one of the most emotional moments" of Pope Francis' trip to the hospital, identifying the girl as 15-year-old Alexia Garduño. She reportedly suffers from osteosarcoma, a form of bone cancer.

Watch the stunning serenade below:

While at Federico Gomez Pediatric Hospital, the pontiff also hugged and visited with other children, even taking a moment to help give a little boy his medication.

The pontiff delivered a brief address the children and staff at the pediatric hospital, asking God to bless them and expressed hope that their "smiles grow day by day" as they seek and receive compassionate treatment.

Pope Francis, whose birthday is today, calls salvation a free gift that "cannot be bought." (AP Photo/Cliff Owen)

"I ask God to bless you, and to accompany you and your families, and all those people who work in this home  and try to ensure that your smiles grow day by day," he said. "May God bless each person…not only doctors but also those who provide 'kindness-therapy' thus making the time spent here more enjoyable."

Pope Francis will be in Mexico until Feb. 17.