RIO DE JANEIRO - At least 64 people were killed and 81 were arrested Tuesday in a large security operation against the Comando Vermelho criminal group in the Complexo do Alemao and Penha favelas in Rio de Janeiro, official sources said.

The Rio de Janeiro state government called the action the deadliest operation in Rio's history. More than 2,500 civil and military police officers took part in the operation, targeting 26 communities across the two complexes.

Officials said the fatalities included 56 alleged Comando Vermelho members and several police officers. Authorities seized 31 rifles as well as other weapons, ammunition and explosives.

Police sought to execute 69 arrest warrants and 180 search warrants tied to an investigation that lasted more than a year. Among those detained was a suspected Comando Vermelho leader accused of fomenting violence in the Chapadao area.

Claudio Castro, governor of the state of Rio de Janeiro, described the operation as the state's response to what he called "narcoterrorism", and said its aim was to stop the gang's territorial expansion into Rio neighborhoods and neighboring municipalities.

Authorities reported that gang members used drones to drop explosives on security forces and civilians in the Penha complex. The operation deployed helicopters, drones, armored vehicles, demolition units and ambulances.

Local prosecutors said Comando Vermelho uses favelas adjacent to expressways as strategic bases for drug and arms trafficking. The public prosecutor's office filed charges against 67 people for drug-trafficking association and three for torture.

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Police said the operation was ongoing and that more wounded had been reported.