It is one of those split-seconds that shatter lives. And there’s always a tiny part of me that is grateful that I have never found myself in that kind of situation.

And now it has happened again.

A teen is crossing a street in Sharon Hill. Then a car appears, seemingly out of nowhere.

I don’t know if the girl ever saw the car. Or if the driver ever saw the child crossing the street.

What we do know is that the car struck the 16-year-old at the intersection of Chester Pike and Laurel Road. The girl was killed as her horrified friends, who were just a bit behind her, looked on.

At that point the driver of the car had a decision to make. It’s one luckily most of us will never have to make. And it’s one in which most of us know exactly what we would do. We would stop and give aid. At least that’s what most of us hope we would do.

That’s not what the driver did last night. The driver fled the scene. But he or she left some things behind. A side mirror was found at the site, as was some of the car’s front grill.

Police this morning say they are looking for a black or dark blue Mercedes or BMW.

I suppose it’s possible that the driver maybe didn’t realize what had happened, that a girl had been struck. But given the damage that’s a little hard to believe.

Maybe they just panicked.

We don’t really know. What we do know is that two lives changed in that instant. One life was lost; another was drastically altered.

And friends and families now are left to deal with the aftermath.

For now the hunt is on for the driver who struck the girl and then left the scene.

And the rest of us are left to think about what we’d do in a similar position.