Mexican Drug Wars: When Media Silenced, Twitter Alerts Citizens

"Twitter mobile is what drives the site's adoption rate, especially overseas," said Lacy. "When there isn't a proper infrastructure to support DSL or high speed Internet, mobile Twitter becomes the application of choice. There is a reason that protests and movements adopt Twitter -- it's because with one text, you can post to the site and there is no telling how many people will see it. It just goes viral."

While the University of Miami's Bagley says social media can be effective in these sorts of situations, he also warns there will be some sort of retribution by the cartels.

"You can expect that there will be a counterattack, and an effort of intimidation towards those [civic] leaders who emerge as the most important," Bagley said.

"I've posted some things to Twitter," said a man living in Reynosa who, fearing for his safety, only wanted to be referred to by his nickname, D.A. "But in the end, it comes down to making the right decisions. For example, not going out at night and tempting the devil."

It is a battle, and much of it is being fought online.

"The videos show the truth, and the truth will set us free," said Mendez.