MONTERREY, MEXICO (AP) -- Authorities in northern Mexico say they are searching for another seven suspects in an arson fire at a casino that killed 52 people.

Nuevo Leon state Gov. Rodrigo Medina says at least 12 people were involved in the attack in the city of Monterrey.

Medina made the comments Tuesday as officials showed journalists five alleged members of the Zetas drug cartel who have been arrested in the case.

Gunmen on Thursday ignited gasoline at the entrance to the Casino Royale. Terrified customers and employees ran deep inside the building.

Many were found dead from smoke inhalation in offices and bathrooms.

Police are investigating whether the attack was in retaliation for not paying extortion money.

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