Mexico's drug cartels have changed tactics and are turning more attacks on authorities, rather than focusing their fire on rivals gangs, the country's top security official said.
Interior Secretary Fernando 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," Mr 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 long said that more than 90% 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.
Mexican drug gangs were 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 organised crime.
But such high-profile attacks were rare in comparison to inter-gang warfare. But after the large-scale attacks on officials on Friday and Saturday, "casualties among the authorities are beginning to increase in this battle", Mr Gomez-Mont said.