Attacks on Civilians in Tamaulipas

An attack on a bus full of civilians was part of a bloody night that left 18 dead in Padilla, Tamaulipas. For some reason, terrorist attacks with guns in Mexico get much less attention than any sort of attack with bombs (see the virtually ignored shootings at El Ferrie and Juanas in Torreón last year for more examples of this phenomenon), but, assuming it wasn't a case of mistaken identity, this would seem to be a terrorist act by any reasonable definition. No word on which group was behind it, but this is in the region being contested by the Zetas and the Gulf.