NEW : Two of the arrested were responsible for payout ; two acted as lookouts , official says . Four family members of 3rd Petty Officer Melquisedet Angulo Cordova were killed . Early Tuesday , gunmen entered the family 's home and opened fire , killing Angulo Cordova 's mother , sister and aunt . Tabasco attorney general says slayings were an act of revenge carried out by Los Zetas . Score: 6
NEW : Two of the arrested were responsible for payout ; two acted as lookouts , official says . Four family members of 3rd Petty Officer Melquisedet Angulo Cordova were killed . Tabasco attorney general says slayings were an act of revenge carried out by Los Zetas . Score: 6