A transit cop in Sheepshead Bay was heralded yesterday for saving the life of a teenager who collapsed on a subway platform last month.

Video taken on August 15th shows Officer Qiang Shi administering CPR to 19-year-old Rio Ferrer on the Q/B platform bound for Stillwell Avenue. Shi says he was at his post that day when a woman reported that the teen had collapsed on the platform. He called for an ambulance, ran upstairs and administered chest compressions and mouth-to-mouth breathing.

“When I went upstairs, I saw his face. It was all bloody,” Shi, who is 34 and has been a cop since 2013, said. “His face was all purple, he wasn’t breathing. (My) first reaction was to try to get him to breathe again.”

Eventually, the teen started breathing again. "After I heard the gurgle, I was like, ‘Oh, thank you, just stay with me. Just don’t go to sleep,’” Shi said.

You can see video of the rescue below:

Ferrer, who has a history of heart trouble, was transported to Coney Island Hospital, where he is expected to make a full recovery. His mother, Dianne Ferrer, called Shi her "guardian angel" in a letter to the NYPD—yesterday, she and her family met Shi in person at the Sheepshead Bay station and thanked him. "I was speechless. There is not any words or word that I could say to really tell him how I feel, how a mother feels knowing that someone saved her child’s life," Ferrer said. You can read the whole letter below:

Dear Chief Fox, On August 15th, 2015, I experienced a mother's nightmare. At approximately 1:00 pm while waiting for a train at the MTA Sheepshead Bay station in Brooklyn (B & Q lines), my nineteen (19) year old son Rio Ferrer collapsed onto the train platform and went into cardiac arrest. As he lied on the train platform his heart stopped beating and he stopped breathing. People on the platform called 911 and ran downstairs from the elevated platform to seek assistance. Appearing on the platform moments later is New York City Police Officer Qiang Shi shield #16871 of the NYPD Transit District 34, who I refer to now as my son's guardian angel on that day. Officer Shi quickly assessed the situation and started CPR on my son. He did so as my son lied a couple of feet from the edge of the train platform as trains pulling into the station sped by. He did so despite the area around my son's chin being covered in blood due to a gash he suffered from his fall to the train platform. Officer Shi was calm, cool, and collected as he performed CPR, radioed for an ambulance, and kept the area around my son clear on that extremely hot August afternoon so my son could breath air once he was revived. When my son started breathing again Officer Shi spoke with him letting him know he was not alone and encouraged him not to go to sleep as they waited for medical assistance.

Police Officer Shi reacted quickly minimizing the time my son's brain was without oxygen. Because of his actions my son did not suffer permanent brain damage. He does suffer from memory loss, which will hopefully come back in time. He is still hospitalized but recovering everyday. He has a second chance at life thanks to the heroic actions of New York City Police Officer Qiang Shi who was equipped with CPR training, compassion, and professionalism.

Police Officer Shi is a true hero and an excellent example of a New York City Police Officer. I am sharing my story with hope that the New York City Police Department recognizes him for his heroic actions. I would greatly appreciate the department arranging a meeting where I can meet Police Officer Qiang Shi and thank him in person for his heroic actions and for saving my son's life.

I am providing you with a link where you can view the actions of Police Officer Qiang Shi on youtube.com.

Respectfully an eternally grateful mother,
Dianne Ferrer

Ferrer's 10-year-old brother also made Shi a police shield out of LEGOs. "I’m really happy that he was there to save my brother’s life," he said.