Interior Secretary Fernandez Gomez-Mont said at a news conference that two back-to-back, bloody ambushes of government convoys - both blamed on cartels - represent a new tactic.
"In the last few weeks the dynamics of the violence have changed. The criminals have decided to directly confront and attack the authorities," Gomez-Mont said.
"They are trying to direct their fire power at what they fear most at this moment, which is the authorities," he said.
Officials here have long said that more than 90 percent of the death toll in Mexico's wave of drug violence - which has claimed more than 22,700 lives since a government crackdown began in December 2006 - are victims of disputes between rival gangs.
In the Juarez area alone, the unrelenting death toll stemming from turf battles between the Sinaloa and Juárez drug cartels is nearing the 5,000 mark.
Daniel Borunda of the El Paso Times writes that so far this year there have been more than 760 murders in the Juárez area; the number of homicides there since 2008 now stands at 4,992.
That is far more than the number of U.S. troops killed during the Iraq War.
And there appears to be no sanctuary. On Saturday night, at a funeral vigil for a slain teenager in the southern part of Juárez, gunmen burst in and opened fire; three people were killed, including a 60-year-old woman, and 10 others wounded.
Official Says U.S. Must Do More to Stop Illicit Trade in Weapons and Money
Mexican drug gangs have been known to target security officials. The nation's acting federal police chief was shot dead in May 2008 in an attack attributed to drug traffickers lashing back at President Felipe Calderon's offensive against organized crime.
But such high-profile attacks were rare in comparison to inter-gang warfare. But after the large-scale attacks on officials Friday and Saturday, "casualties among the authorities are beginning to increase in this battle," Gomez-Mont said.
On Saturday, gunmen armed with assault rifles and grenades attacked a convoy carrying the top security official of the western state of Michoacan, in what appeared to be a carefully planned ambush.
The official survived with non-life-threatening wounds - she was traveling in a bullet-resistant SUV - but two of her bodyguards and two passers-by were killed. Of the other nine people wounded, most were bystanders, including two girls ages 2 and 12.
Gomez-Mont said the attack was carried out by a group known as "The Resistance," an outgrowth of the Michoacan-based La Familia drug cartel.
It came a day after gunmen ambushed two police vehicles at a busy intersection in the northern border city of Ciudad Juarez, killing seven officers and a 17-year-old boy caught in the crossfire. Two more officers were seriously wounded.
"This will happen to you ... for being with El Chapo Guzman and to all the dirtbags who support him. Sincerely, La Linea," the message read. The authenticity of the message could not be independently verified.
Gomez-Mont, who is responsible for domestic security affairs, said the United States has to do more to stop cross-border gangs and illicit trade in weapons and money.
He said some gangs "find a certain kind of sanctuary on the other side of the border," referring to Los Aztecas, a Ciudad Juarez gang that also operates in the United States, where it is known as the Barrio Azteca gang.
"They (the United States) contribute very important components in the dynamic of violence," Gomez-Mont said.
"We need the Americans to step up and recognize the fact that it is their money, their drug demand, that foments and encourages the violence in Mexico. We need the Americans to assume their responsibility," he said.
The U.S. has supported Mexico's offensive, providing helicopters, dogs, surveillance gear and other law-enforcement support through the $1.3 billion Merida Initiative. "That is not a small amount, but it is not sufficient," Gomez-Mont said.
A few hours before his comments, the military reported that Mexican soldiers killed five men Saturday in a shootout with assailants in a town near the northern city of Monterrey and detained six police officers on suspicion of helping the attackers. The Defense Department alleged the police tried to interfere with the troops during the confrontation.
Drug cartels are known to operate in the area, and many members of local police forces are suspected of aiding the gangs.
In the Pacific coast state of Guerrero, a drive-by shooting killed the local leader of the tiny Labor Party outside his home Sunday, state police reported. Former legislator Rey Hernandez Garcia was hit by seven gunshots.
Police did not offer any information on a possible motive in the attack.