WASHINGTON ( CNN ) -- The Justice Department on Thursday announced 300 additional arrests in a four-year operation that it says produced nearly 1,200 arrests and seizures totaling 11.7 tons of illegal drugs . Authorities look through seized property after a drug raid at a house near Atlanta , Georgia , on Wednesday . Attorney General Eric Holder announced the wrap-up of Project Coronado , which resulted in arrests in 15 states in the past two days . Holder said the operation targeted the distribution network of a major Mexican drug trafficking organization known as La Familia . About 3,000 federal agents participated in the investigation and raids , officials said . `` This unprecedented , coordinated U.S. law enforcement action -- the largest ever undertaken against a Mexican drug cartel -- has dealt a significant blow to La Familia 's supply chain of illegal drugs , weapons and cash flowing between Mexico and the United States , '' Holder said in a news conference . Watch Holder announce the arrests » . Michele Leonhart , acting chief of the Drug Enforcement Administration , said the cartel was known for specializing in the trafficking of methamphetamine and for its brutal violence , including beheadings . Authorities said the arrests made Wednesday and Thursday occurred in California , Colorado , Georgia , Massachusetts , Minnesota , Mississippi , Missouri , Nevada , New York , North Carolina , Oklahoma , South Carolina , Tennessee , Texas and Washington . Dozens of arrests occurred in the Dallas , Texas , area where agents with the Bureau of Alcohol , Tobacco , Firearms and Explosives filed charges against cartel members believed to have illegally purchased and shipped high-powered firearms to the cartel , which was based in the Mexican state of Michoacan . U.S. officials vowed to indict cartel leaders and extradite them to the United States . One leader , Servando Gomez-Martinez , was indicted in New York on Thursday . He remains at large , and is presumed to be in Mexico . A senior law enforcement official involved in the operation , who asked not to be identified , said he was certain the latest crackdown on La Familia would affect the methamphetamine market in the United States for months . `` It 'll make a difference not only because of how hard we hit 'em , but where we hit 'em , '' the official said . Another official said during the course of the investigation that labs run by La Familia had been discovered in Atlanta , Georgia , and San Jose , California . To date , Project Coronado has led to 1,186 arrests in 44 months . During that time , agents seized $ 32.8 million in U.S. currency , and about 1,225 kilograms ( 2,700 pounds ) of methamphetamine , 2,000 kilograms ( 4,409 pounds ) of cocaine , 13 kilograms ( 29 pounds ) of heroin and more than 8 tons ( 7,200 kilograms ) of marijuana .
In past two days , Project Coronado resulted in arrests in 15 states . Officials : 4-year operation produced nearly 1,200 arrests , 11.7 tons of cocaine seized . AG says operation targeted La Mafia , a top Mexican drug trafficking group . Law enforcement officials : Crackdown will target methamphetamine market in U.S .