The bomb-maker, surely got his components from somewhere, I'll bet law enforcement is checking hardware stores, Home Depot, places like that. Also, nowadays, people can buy things online. A sophisticated bomb-maker sadly. Actually, Louisiana Government even sent out a warning to their residents when the second explosion happened. So, really, this could happen about anywhere at this point. The USA article says they found a backpack. Maybe that will have some sort of evidence.
That cyclists got hit, must have scared the beejeebers out of them, this shows, this is likely now, pretty random in whom the terrorist bomb-maker targets.