Gunmen ambushed a prisoner transfer convoy in western Mexico at the weekend killing eight officers in a failed attempt to free a high-level cartel member.
At least 20 assailants launched a running gun battle against a column of vehicles escorting nine prisoners as it raced between an airport and penitentiary in the Pacific coast state of Nayarit.
As police lay dying in a string of bullet-riddled pickups, part of the convoy stopped and turned to fight off the attackers, said General Rodolfo Cruz, head of support operations for the Federal Police.
"The rest of the convoy stopped and opened fire on the attackers, who fled in all directions when they saw their attack being repulsed," Gen Cruz said. The fallen officeers "gave the most sacred thing a human has, their lives."
Police called it a well-planned attack intended to free Jeronimo Gamez, cousin of Arturo Beltran Leyva, the reputed leader of one of Mexico's most powerful cartels. Gamez was arrested in Mexico City in January and was being moved to a prison in Nayarit's capital city, Tepic.
Officers managed to deliver Gamez and eight other detainees to the prison despite the attacks which began just outside the airport.
Four federal police officers, two federal investigative agents and two prison employees died in the attack. There was no immediate information on the number of injured or wounded and no reports of deaths or arrests among the attackers.
Prosecutors accuse Gamez of acting as Beltran Leyva's representative in negotiating drug deals with Colombian traffickers.
The attack came three days after a bold assault on an army patrol in the nearby state of Guerrero, where 15 assailants and one soldier died, and just a day after officials reported 12 people dead across the state of Michoacan, including three who were beheaded.
The assaults by heavily armed cartels bracketed the first official visit Thursday by U.S. President Barack Obama, who vowed to step up enforcement of laws banning the transfer of guns across the U.S.-Mexico border.
Mexico has suffered a continuing wave of drug-related violence, killing more than 10,650 people since 2006, when Calderon sent 45,000 troops to directly confront the traffickers.
As if to illustrate the scale of the drug war being fought in Mexico, federal police staged a massive operation using 400 federal officers, two Blackhawk helicopters and an airplane to raid a baptismal party being held Saturday by alleged members of the Familia Michoacana cartel.
Police detained 44 people, including a man allegedly in charge of recruitment for the Michoacan-based gang.
Federal police commissioner Rodrigo Esparza said that suspect Rafael Cedeno claimed to have trained 9,000 recruits for the cartel in 2008, hinting at the gang's size and power.
True to the gang's quasi-moralistic tone - it has claimed in the past to oppose common crime - Cedeno claimed the training involved instilling "moral and ethical values" in recruits, including family unity and shunning alcohol and drugs.
Many of the people attending the baptism party at a Morelia resort were released, and the other 43 people were being held based on their presumed involvement in the drug gang.
The White House last week added the Familia Michoacana to the US government's blacklist of drug syndicates, known commonly as the Drug Kingpin Act.
US officials say the gang moves massive amounts of cocaine from Colombian drug dealers. Mr Esparza said Cedeno was also in charge of shipping methamphetamine precursor chemicals through Pacific coast ports and oversaw hit squads in the region to fight off the rival Gulf cartel.
AP