MEXICO CITY--Two Mexican federal police officers were killed and nine injured in an ambush in a drug cartel-dominated section of Michoacan state, authorities said. The attack, by unknown assailants, occurred a few hours after Mexico's finance minister declared that "the rule of law" was under threat in the troubled state. The officers were attacked Wednesday night near the city of Apatzingan, where the cult-like Knights Templar drug cartel has seized control of much of the local economy and challenged the power of local government. The Templar cartel control methamphetamine production and trans-shipment in the western farm state, and also run a vicious and widespread extortion racket that has targeted mom-and-pop tortilla vendors and large businesses. According to federal officials, a group of police were traveling in a convoy on a curvy highway after sunset when they were fired on by a number of individuals hidden in the surrounding hills. Soon after, army troops were reportedly sent to a nearby federal power plant to protect it. In late October, a number of power installations were bombed in the state, presumably by cartel members, in a show of force that resulted in widespread blackouts. Michoacan has long been a troubled state, but the security situation has deteriorated significantly since President Enrique Peña Nieto took office late last year. Earlier statements by his cabinet members have sought to downplay the trouble. But on Wednesday, Finance Minister Luis Videgaray appeared to acknowledge the depth of the problem. The challenge isn't only for Michoacan. The challenge is for all Mexicans," he said. Today in Michoacan, the Mexican state is threatened, the rule of law is threatened, and we are confronting one of the great challenges that the nation faces. Armed "self-defense" groups have popped up in numerous towns in Michoacan to try to ward off the cartel presence, but some locals complain that the vigilantes have created another armed threat to government power. Earlier this month, the Peña Nieto government deployed troops and seized the busy Michoacan port city of Lazaro Cardenas, which was believed to be largely under Templar control. Hundreds of local police suspected of corruption or collusion were also arrested. In an interview Thursday with the news service Milenio, José Manuel Mireles, a leader of one of the self-defense groups, said that the latest attack was probably the Knights Templar's protest against the federal presence, particularly new roadblocks that have threatened the group's ability to conduct business. In a separate incident Wednesday, two state police officers and a civilian investigator were injured when they were attacked by unknown assailants. State government officials said the victims had been on their way to a mine to investigate allegations that it had been illegally seized, presumably by an organized crime group. Colombia recalls envoy to Nicaragua amid dispute about Caribbean Cecilia Sanchez of The Times" Mexico City bureau contributed to this report.