Dashcam footage shows moment police officer resuscitates choking baby

The incredible moment a police officer revives a choking baby has been captured in dashcam and bodycam footage.

The officer, Nick St Onge, responded to a call for help from a Georgia woman who said her two-month-old granddaughter was conscious but not breathing, Marietta Police said in a statement.

The baby was lifeless and turning blue when he arrived - so Mr St Onge, who had recently completed a first aid course, began administering back blows and chest thrusts.

After an anxious two minutes, with the grandmother pacing back and forth, the infant began to breathe and cry. She is expected to make a full recovery.

"We prepare for those moments where people's worlds turn to chaos," Mr St Onge told ABC News.

"I knew pretty much from the get go I was probably going to be the first one on scene."

Mr St Onge says it was "three minutes of terror" followed by a lot of joy.

"I'm just the guy who showed up to do what he had to do."