Monterrey: A kidnapping gang linked to a drug cartel used a municipal jail in the northern Mexican state of Nuevo Leon to hold hostages while it negotiated ransom, officials said.
Four police officers in the city of Benito Juarez have been arrested and 17 others are under investigation, Nuevo Leon state Security Council spokesman Jorge Domene said.
"The four officers who were in charge of that section (of the jail) are under preventive arrest and the people who had been kidnapped were freed," Domene said.
The four officers "worked for Los Zetas", considered Mexico`s most violent drug cartel, Domene said.
Army troops following up on a tip rescued two people who had been kidnapped and taken to the jail.
"You have to remember that this is not the first time we have intervened in the city of (Benito) Juarez," Domene said, adding that the city`s police headquarters has been occupied by the security forces four times as part of efforts to root out corrupt officers.
Army troops and marines have arrested 172 police officers in seven cities in Nuevo Leon in the past week as part of an anti-corruption operation.
Of the officers detained, 73 are under preventive arrest and the other 99 are slated to undergo background checks to determine whether they should keep their jobs.