Buses ablaze in Rio as gangs hit back

Gang violence has exploded in Rio de Janeiro, with several public buses and cargo trucks set alight on a highway.

Black smoke filled the air after eight buses and two cargo trucks were engulfed in flames on Tuesday (local time), in a northern part of the city.

It's believed the attack was retaliation for a large anti-drug operation by police, military police spokesperson Major Ivan Blaz said.

The suspects were wearing ski masks and ordered everyone off the buses and trucks before setting them ablaze, according to authorities.

More than 40 people since been arrested and 30 automatic rifles were recovered by authorities.