Six out of ten Mexican prisons are “self-governed” by prison gangs, a new study from the National Commission on Human Rights in Mexico says, following a massive breakout of 131 inmates from a prison in northern Mexico, coordinated by the Zetas drug cartel, the Associated Press said.

More than 500 inmates have escaped Mexican jails since 2010, the AP also reported.

The Commission visited 100 state and local prisoners for the report and found that the gangs, not the prison guards or authorities, are the ones running the joint. They control everything from Internet security to the food the inmates eat.

In a statement to reporters, Human Rights Commission Representative Andres Aguirre told Reuters that 60 percent of the country’s 430 prisons suffer from overcrowding, shortage of guards and corrupt guards and officials who sometimes aid in the mass escapes.

The total population of Mexico’s jails as of July totaled 48,872 inmates, Reuters said.