Brazilian officials investigate a fatal helicopter crash that kills six people after two helicopters collide midair over a suburb of Rio de Janeiro on Sunday, according to multiple outlets. Authorities inspect the crash site as part of the ongoing investigation. Reports state that the collision occurs over a suburban area near Rio de Janeiro, and that the incident prompts officials to secure and examine the wreckage and surrounding area. One police investigator quoted at the scene says preliminary consideration includes the possibility of human error as a factor in the collision. Officials continue work to determine the precise circumstances leading to the crash, including how the two aircraft came into contact and what, if any, operational or procedural issues may have contributed. The investigation is ongoing, and authorities have not reported a definitive cause in the accounts summarized by these sources.