Six gunmen gained access to a Mexican prison after midnight on Jan. 3, killed four inmates in their sleep, and then tried to shoot their way out, sparking a melee that left five of the attackers dead.

The assailants infiltrated the ironically named Social Rehabilitation Center (CERESO) in Tuxpan, disguised in uniforms of the Guerrero state Ministerial Police, telling guards they were bringing in a prisoner. Army troops were subsequently sent in to secure the facility. The slain inmates were said to be serving time on drug trafficking and kidnapping charges. This is the latest in a wave of cases of cartels taking their bloody turf wars to the inside of Mexico's prisons.

The night after the raid on the Tuxpan CERESO, a vehicle carrying the body of one of the slain inmates back to his home for burial was intercepted by an armed commando on the highway and set afire. The body was burned beyond recognition. 

In the neighboring state of Oaxaca last month, another massacre was reported -- 11 local campesinos found slain, their bodies stuffed in a Chevrolet Suburban in the rural municipality of Santiago Juxtlahuaca.