BROOKLYN - A Sheepshead Bay family thanked police Wednesday after an officer helped their son survive a heart attack.

Officer Qiang Shi reportedly performed CPR on the teen after he collapsed on the Sheepshead Bay BQ subway platform on Aug. 15. A witness captured the ordeal on camera and posted it to YouTube.

The teen, 19-year-old Rio Ferrer, went into cardiac arrest. His heart reportedly stopped twice, and without Shi's actions, Ferrer's mother says her son would have died.

"To me, police Officer Shi is my son's guardian angel," says Dianne Ferrer. "He was placed here at the station at that time to watch over my son, and in this incident where he saved my son's life."

The Ferrer family met with the officer on the platform to thank him Wednesday afternoon.

Ferrer's mother even presented Shi with a piece of handcrafted art.

Shi says he thought he'd lost Ferrer until he heard a guttural noise while performing CPR.

Ferrer, who remains hospitalized, is expected to be OK. He called Shi on the phone to thank him.