A 2-year-old girl is in serious but stable condition after falling from a third-floor apartment window in Borough Park. 

Officials say the child, identified as Nyjeana Civil, fell 30 feet to the sidewalk near 44th Street and Ninth Avenue on Wednesday. Witnesses report hearing her scream for just a few seconds before going silent. 

An 18-year-old passerby is being hailed as a hero for administering CPR. 

Ashley Giron says she immediately knew the fallen child required resuscitation after checking for a pulse. After a few moments, Nyjeana began breathing again, Giron says.

However, the teen says she has never received any formal training for the technique and learned it on her own from the Internet and the TV show "Grey's Anatomy." 

First responders say the child was rushed to Lutheran Hospital with head and neck trauma, as well as cuts and bruises. 

There is a guard on the window, as required by law when landlords own three or more buildings, but the screen has a hole in it. 

The girl's mother was home at the time. Police do not suspect any criminality, but the investigation is ongoing.

The FDNY and the Red Cross both offer CPR and first aid training courses.