Was there ever an explanation about the Black SUV & Picture Memorial? [Spoilers possible]

At the beginning the kid drops off the picture.....swings back and the picture is trashed....then the black SUV darts after he attempts to take a picture of it......what was that all about? Did the Desire gang murder his mother? Why did they trash the picture memorial? Maybe I fell asleep, I must have missed that....anyone have a thought?