At least six people were killed on Sunday after two helicopters collided mid-air and crashed west of Rio de Janeiro, according to Brazilian firefighting authorities.

Officials said all occupants aboard the two aircraft were killed in the accident, while investigators continue to examine the circumstances surrounding the collision.

According to a source within the Brazilian police cited by Agence France-Presse, American singer Oliver Tree was listed among the passengers on one of the helicopters.

Police noted that the victims have not yet been formally identified because the bodies suffered severe burns, requiring further forensic examinations before official confirmation.

Brazilian authorities are expected to release additional information as the investigation progresses.