Like most teenagers, Chenelle Agnew is obsessed with her smartphone. So when it slipped out of her hands while she was standing on the Bergen Street subway platform in Brooklyn Thursday afternoon, she did what any reckless teen would do.

She jumped onto the tracks to get it.

Then a train came barreling down on her.

Luckily, the 17-year-old escaped with her life — and all her limbs intact.

Agnew was standing on the northbound platform of the Bergen Street station on the 2/3 line at about 2:20 pm when the phone fell out of her hands.

“I saw her in the tracks trying to pick something up. And then I heard her hit. I heard the thump,” said the train’s operator, Devone Mason.

“I didn’t know if she was alive or dead.”

But when Mason looked under the car, she found Agnew scratched up but mostly OK — and still holding onto her phone.

“She was down there still moving,” said Mason, who added that it was the first time in her 17 years driving a train that someone fell under it.

“I’m still a little jumpy,” she said.

Emergency workers arrived and pulled Agnew from under the train and onto a stretcher.

The teen continued to look at her smartphone the whole time. Once she was outside and had cell service, she started making calls.

Emergency medical personnel took the girl to Methodist Hospital.