"They're losing money and they are frustrated, and they are using other tactics to get their loads across," Escalante said.
When authorities stopped a vehicle in Douglas, Ariz., several weeks ago, traffickers on the Mexican side of the border "laid down suppressive fire" to stop U.S. officials from advancing, enabling the vehicle to make it back across the border with a load of marijuana intact, one Immigration and Customs Enforcement official said in an interview.
Arizona Atty. Gen. Terry Goddard said there appeared to be a shift in the rules of engagement on the part of traffickers affiliated with Sinaloa and other cartels.
"They've got to get the dope through, or they won't get paid. . . . These guys are under orders. . . . They have rules of engagement and they follow this direction."
One member of the Shadow Wolves, American Indian trackers who patrol the Tohono O'odham reservation for the Department of Homeland Security on the Arizona border, said that in the past, weapons were largely used by traffickers to protect themselves from bandits.
"But lately, [the bulletins have warned] that they've been carrying them to engage law enforcement," the tracker said.
Meyer was on assignment in Arizona.
Times staff writer Sam Quinones in El Paso and Los Angeles contributed to this report.