At least 64 people were killed in a police operation against the Red Command gang in Rio de Janeiro's northern suburbs - the largest and deadliest raid in the Brazilian state's history. Four police officers were among those killed during Operation Containment in the Alemão and Penha districts, state Governor Cláudio Castro said. More than 80 people were arrested.

Fierce clashes erupted when about 2,500 security personnel moved in on Tuesday morning. The Red Command (Comando Vermelho) responded with gunfire, burning barricades and dropping bombs from drones, officials said. The UN Human Rights Office said it was horrified by the police operation, urging prompt and effective investigations.

The area of favelas near Rio's airport is considered to be the headquarters of one of Brazil's most powerful organised crime groups. State officials reported that a significant number of those killed were suspected gang members while dozens of civilians were also injured in the violence.

Local residents described the area as a war zone, with roads remaining closed and many fearing further escalations in violence due to the gang's increasing territorial control. During the raid, police seized over 200kg of drugs and numerous firearms.

The joint operation by civil and military police follows a year-long investigation, and such large-scale police actions are anticipated ahead of international events in Brazil, including the upcoming UN climate summit in November.