Presumably in response to the mass graves found outside the state capital, 100 marines have deployed to Durango.
Mexico has long had a problem with its security policy being determined in large part by media attention, something that always struck me the ignorance of the worsening situation when I lived in Torreón. This seems a pretty good example of the same phenomenon. Because the mass graves in San Fernando were discovered first, because the murders were allegedly perpetrated by an identifiable villain, and because they formed a story of inexplicable cruelty, Tamaulipas announced the creation of three new military bases and the deployment of more than 500 soldiers (not sure of the exact number, because the train deployment didn't include any numbers on the number of troops). But more bodies were discovered in Durango than in Tamaulipas, and the number of murders has recently been comparable, despite Durango having just over half the population that Tamaulipas does. Perhaps there is another explanation for the disproportionate responses beyond the discrepancy in media attention, but I can't think of one, and that's not a good way to make policy.