Three killed as firefighting helicopters collide in California

California: Three people have been killed as two firefighting helicopters collided in the US state of California.

According to foreign media, one helicopter crashed and landed safely in Riverside County on Sunday evening, while another helicopter crashed.

The report states that all three people on board the crashed helicopter were killed.

Both helicopters were working to extinguish wildfires in southern California.

According to the National Transportation Safety Board, an investigation is underway to determine the cause of the accident.