UPDATE: The officers met with mom & the boy she named Chris the day after the Christmas delivery.

Southeastern Pennsylvania Transit Authority officers jumped into action to help a mother deliver the ultimate Christmas gift Thursday evening — a baby boy.

The delivery happened around 6 p.m. on a Market Frankford Line subway train underground in Center City Philadelphia as an eastbound train approached the 15th Street stop.

"When she was on the train I guess the baby said, 'I'm ready to come out now," said witness Toney Harris-Saunders who was on his way to see family for Christmas.

Harris-Saunders, a 26-year-old Philadelphia resident, said he called 911 when he saw the woman having the baby in the seat in front of him — calling the entire experience a "phenomena."

"I helped relax her and a couple of other people helped her as well ... told her to relax, to take some breaths," said Harris-Saunders.

That's when the train stopped and SEPTA police officers stepped in.

After the delivery, mother and baby were taken to nearby Hahnemann Hospital in good condition.

"Officer, hey, somebody's having a baby," said SEPTA Officer Daniel Caban.

"Inside I was just praying for the medics to come in," said Caban.

"Everything just happened so quick but it was amazing, said SEPTA Officer Darrell James.

The officers delivered the baby, removed the umbilical cord from the boy's neck and then placed the boy in his mother's arms as the boy's father removed the shirt off his back to keep his son warm.

SEPTA Police Chief Thomas Nestel III tweeted his department’s excitement over the special delivery.

"It was wonderful," said witness Erek Cunningham. "They cuddled the baby, rushed it into the ambulance. Took very good care of him."

No word yet on what the boy's parents will name him.