Seanan picks the bus crash suspects:
#10 on her list? The Decepticons.
Veronica's classmates weren't the victims of any human agency -- they were, instead, just innocent bystanders in a war much larger than this puny planet. The mild-mannered school bus that drove them to and from Sharks Stadium was actually Yellowtail, an Autobot masquerading as a school bus to get a look at some stealthy Decepticon plans. Unfortunately for everyone involved, he got spotted, locked into auto-form by an evil ray gun, and then, at the opportune moment, blown to hell. That whole rat thing is actually the Autobot idea of an air freshener; after all, decaying biomatter eventually becomes motor oil. Sort of like robot potpourri. When Veronica discovers the secret war going on all around her, it's only a matter of time before she gets drawn in, befriends a transforming car, and starts making the galaxy safe for truth, justice, and giant robots once again.