Soldiers apprehended two additional suspects in the Aug. 25 arson attack on a Monterrey casino left 52 dead, the Mexican military said.

Antonio Camacho Jaco and Gerardo Alejandro de Leon Jimenez were nabbed here last weekend, bringing to 15 the number of people in custody in connection with the blaze, a spokesman for the 7th Military Zone said.

The army identified both men as members of the Los Zetas crime organization and said they were tied to murders, kidnappings and drug trafficking in Monterrey and the surrounding state of Nuevo Leon.

Los Zetas gunmen torched the Casino Royale because the gaming establishment's owner refused to pay protection money.

The gunmen told the people inside the casino to get out before setting fire to the building, but the emergency exits were closed. The majority of the 52 victims died from smoke inhalation, with only seven burning to death.

Camacho carried the gasoline into the casino, while De Leon robbed patrons before the fire was set, the military said.

The pair were acting on the orders of Jose Alberto Loera Rodriguez, arrested early this month as one of the alleged masterminds of the attack.

Founded by deserters from an elite special forces unit, Los Zetas began as the armed wing of the Gulf drug cartel, but ended that relationship in March 2010 to go into business for themselves.

Hundreds have died in the ensuing turf battles between the aggressive upstarts and the established drug trafficking organizations.

Separately, soldiers with the 7th Military Zone arrested three other reputed Zetas after a battle in the rural community of Doctor Gonzalez, around 40 kilometers (25 miles) east of Monterrey, where troops found four burned bodies.