A Bay Ridge mother whose 12-year-old daughter was killed while subway surfing is speaking out again as new video shows teens riding on top of trains in Brooklyn.

Video posted to social media shows several teens running across the top of a moving train in Borough Park.

For Natalia Rudenko, the images are painful.

“I was very happy all 13 years. I was happiest mom in the whole world,” Rudenko said through tears. “She never gave me a problem. She never gave me trouble.”

Rudenko’s daughter, Zemfira Mukhtarov, died last October while subway surfing, just days before her 13th birthday.

According to NYPD Transit Chief Joseph Gulotta, there have been 20 subway surfing arrests so far this year, including a 12-year-old who was rescued.

"We work with family court," Gulotta said. "We work with the schools, work with the Department of Education. We double down on everything. We go visit the parents afterwards and really what the drone footage gives us is - I can tell you a bunch of times you get, 'Not my kid,' and then you show him the video, they're like, 'Oh, that is definitely my kid,' and the parent sees it in a different light."

Gulotta said the department is now conducting near-daily drone operations, particularly along the J, Z and M lines in Williamsburg, which he described as a hotspot.

"The drones give us the eagle eye of what's going on up there, and that's really been a game changer for us," Gulotta said. "We go up live. We watch here at Transit headquarters as it's unfolding, we're getting updates of what's going on. We watch live at Transit headquarters as it’s unfolding.”

On Jan. 22, the day one of the videos News 12 obtained was recorded, police said they received multiple 911 calls about subway surfing in Brooklyn and took one child into custody.

Gulotta said the goal is prevention — so no other family has to endure the same loss.

“We was very close,” Rudenko said. “I check who she’s talking to, what picture they sent… nothing bad.”

Rudenko says this could happen to anyone's kid.

The NYPD and Chief Gulotta urge parents to talk to their kids about subway surfing and to call 911 if you see subway surfing.