Harrowing video shows one of the helicopters involved in the mid-air collision that killed American singer Oliver Tree hurtling toward the ground in Brazil — as a witness claimed he saw someone jumping from one of the stricken choppers. The footage released by Rio de Janeiro’s fire department shows one of the aircraft falling uncontrollably near an electric car lot on Sunday morning, sparking a fire that set 20 vehicles ablaze. Six people, including the quirky “Alien Boy” artist, were killed — with one seen jumping from one of the helicopters before both hit the ground, according to witness Fernandes de Freitas.