What's the Name of That Book??? discussion

So there are these kids, I'm pretty sure there are 3 of them, and they die in a car wreck and come back as ghosts. They sink down into the earth if they aren't near where someone died. They're on some sort of mission, but I forgot what. At one point, they find the place where the twin towers once stood, and it's full of ghost kids playing. I think I read it around 2016, and it's a really good book! Thanks for helping me find it!!

Everlost

That was it, thank you!