CIUDAD MIER, Mexico (AP) -- Once again, the bodies are piling up.
At least 14 people died Tuesday in several firefights between federal forces and gunmen in the city of Reynosa, across the border from McAllen, Texas. The dead included 10 alleged gunmen, two federal police officers and two bystanders, Tamaulipas state authorities said.
Gunmen blocked some of the industrial city's main avenues with buses in the afternoon and then ambushed federal police officers on patrol, officials said.
Earlier this month in the border town of Ciudad Mier, gunmen peppered the facade of the main hotel, leaving at least 20 bullet holes in the two-story building. The next day, soldiers killed four of the alleged attackers. A day after that, three other gunmen were found dead near the Rio Grande.
A spasm of violence has left at least 64 dead throughout the northern state of Tamaulipas this month, according to an Associated Press tally of official and Mexican media reports. That has many worried about a return to the worst days of 2010, when the security wing of the powerful Gulf Cartel turned on its former bosses, forming the breakaway Zetas group that has distinguished itself for butchery.
That rivalry simmers along, but authorities say many of the recent killings are the byproduct of a fresh feud between two Gulf Cartel capos, former allies who are struggling for control of cities or stretches of border.
Tamaulipas has always been a focal point in the drug war, one of the busiest places on the border for northbound drugs and migrants and southbound weapons and cash. The federal government sent troops to the state in November 2010, turning military patrols into a feature of life in border cities. The violence has never fully abated, but even by the standards of Tamaulipas, April has been extreme. Mexico's federal government has promised a new strategy, though it has yet to offer details.
"The fact is right now the federal government response in Tamaulipas is nowhere near what it needs to be," said U.S. Rep. Filemon Vela, a Democrat from Brownsville, a city across from Matamoros, which is a 2-hour drive east from Ciudad Mier.
Much of the violence has its roots in the February arrest of Javier Garza Medrano, who oversaw the Gulf Cartel's drug, kidnapping, extortion and gasoline theft activities in the Gulf coast city of Tampico, according to Mexico's National Security Commission. Garza apparently came to believe that a rival in the cartel, Aaron Rogelio Garcia, provided the information that led to his arrest, and ordered the man's murder, according to a government official who spoke on condition of anonymity because he was not authorized to discuss the matter publicly.
Gunmen then opened fire at Garcia's April 3 funeral in Matamoros. The government acknowledged that an 18-year-old woman was killed, but the unnamed official said three people had died, including Garcia's wife, brother and sister-in-law.
Attacks on Garcia's allies followed in Tampico and neighboring Ciudad Madero, the official said. Twenty-eight people were killed in the two cities over four days, 14 of them in a five-hour span during fighting between criminal groups that included drive-by shootings and execution-style killings. Victims were dumped on streets and, in one case, inside an ice-cream shop.
In addition to the Gulf Cartel infighting, several deaths have been attributed to a feud between the Gulf Cartel and the Zetas, while still other people have died in clashes between gunmen and Mexican military units.
Easy access to the U.S. makes Tamaulipas attractive to both foreign manufacturers and criminal organizations. More immigrants enter the U.S illegally here than anywhere else along the border, and in drug trafficking, it's second only to Arizona. Assault rifles purchased at Texas gun shops and cash from drugs sold in other states are smuggled back into Mexico through Tamaulipas. Undeveloped riverfronts like that outside Mier, where the Rio Grande river is shallow and studded with rocks, make crossing easy.
Asked about the cause of the fighting, Mier residents refer euphemistically to those who come from upriver -- Zetas territory -- and those from downriver -- the land of the Gulf cartel.
But nearly everywhere in Tamaulipas, it is impossible to ignore the effects of the violence.
One afternoon in the working-class neighborhood of San Pedro on the outskirts of Matamoros, four women sat chatting outside a boxy single-family home. None would give their names. One said her husband was taken by gunmen 2 ½ years ago. Another said it had been three years since her 28-year-old son disappeared. Yet another recounted when a marine helicopter opened fire from the air, sending residents scrambling for cover.