An off-duty NYPD helped a frantic mother whose infant was choking. 

If not for his brave actions, the baby girl might not be alive. 

"I went out and saw the mom with the baby lifeless in her arms"

Video from a home surveillance camera shows NYPD Officer Freddy Cerpa saving the life of the unresponsive 1-year-old girl. He checked her airway and then patted her on the back until she was breathing again. It happened on Dec. 7 at around 2 p.m. 

Friday at NYPD headquarters, he spoke about his heroic actions, which he called just part of his job. 

"I was home getting ready to go to work," Cerpa said. "I hear banging on my door ... 'Please help my baby.' I went out and saw the mom with the baby lifeless in her arms." 

"It's an amazing feeling"  

The taps to the baby's back he learned during police academy training about a year ago. 

"I felt her chest go up and down, meaning that she's starting to breathe again," Cerpa said. "It's an amazing feeling to know I was able to help save a baby's life before Christmas."

The parents knew they could get help by running to his front door because they are longtime family friends. The couple asked not to be identified.

"They gave me their gratitude about helping them and just let me know the baby's fully recovered," Cerpa said. 

That very same week there was a similar save. On Dec. 10, NYPD Det. Michael Greaney saved a choking 8-month-old girl. That impressive rescue witnessed by many driving by along the Bronx River Parkway.

"Our mission is to preserve life, and I feel that's the most Important part of being a police officer," Cerpa said. 

He said he will remember forever the rush of relief he felt.

Cerpa is assigned to the 43rd Precinct stationhouse in the Bronx. There's one thing he wants every member of the public to know.

"If you have any precautions you want to take, like taking a CPR class there are resources you can find online," Cerpa said.

That's advice from an officer who knows when he's off duty, he's always on call.