Reynosa, which lies across the Rio Grande from McAllen, Texas, is a black hole of information.

What goes on in Reynosa matters. But when it comes to drug war violence, you are unlikely to find out. That’s because the newspapers in the city purposefully do not provide news of public security. It is too dangerous to report.

So last Sunday night, mayhem erupted in Reynosa. The Monitor, McAllen’s newspaper, posted a story later citing a state law enforcement officer saying that “there were four trucks filled with bodies” that gangsters retrieved after a fierce firefight.

Newspapers in Mexico City, like Excelsior, reported only what their journalists could learn about the gunfight on Twitter _ that a “presumed clash between the army and members of the Gulf Cartel” broke out near the state attorney’s office. No mention of casualties.

But you only have to listen to a bit of the 15-minute video above to realize that this firefight was extremely fierce with automatic weapons volleys and hundreds of rounds being fired. It sounds like Fallujah or Kandahar.

Reynosa and McAllen have a combined population of 1.7 million people. It is the third largest metropolitan area along the US-Mexico border. Since it is a major border crossing, truckers are eager to learn about incidents there. Here’s what a blog called Mexico Trucker Online said:

“All hell broke loose Sunday night in the border town of Reynosa, across the river from McAllen Texas as various factions of the Gulf Cartel took to the streets to settle internal conflicts within the group.

“For about 3 hours, gunfire, grenade explosions and convoys of armed combatants were seen and reported through social media sites such as Facebook and Twitter. Not surprisingly, mainstream media in Mexico refrained from reporting the incidents.”

Another blog, called Reynosa Libre, also reported on the gunfight but said it left only four or five people dead. Typically, the blog has no name attached to it, no way to verify its accuracy. But the posting does sum up the lack of information nicely:

“Given the obstinacy of the local media and newspapers _ El Mañana, La Tarde, La Prensa, Metro Noticias, En Linea Directa, the local Tv Azteca and Televisa affiliates, among other outlets _ what we have is a sepulchral silence of the voluntary and involuntary accomplices to that which is occurring here.”

The blogger is pretty harsh. The journalists at those outlets might not survive the week if they went up against Los Zetas and the Gulf Cartel in Reynosa, which by many accounts is totally subjugated to organized crime. As the Los Angeles Times said in this 2010 story, Reynosa is behind enemy lines.

The Tamaulipas governor, Egidio Torre Cantu, visited Reynosa today and Twitter reports and the NarcoViolencia blog say new firefights broke out around 2 p.m. between “armed civilians” _ gangsters _ and federal police. The blog says the cartel henchmen were moving about in 20 vehicles.

Imagine that: A caravan of heavily armed civilians moving around the city, terrorizing the civilian population right on the border of Texas, and no one can provide trustworthy information.