Three people were killed and a fourth was taken to a hospital after a helicopter crashed in the Chatsworth area of Los Angeles on Tuesday evening (local time), the Los Angeles Fire Department said in a social media post.

Four people were assessed at the scene, with three pronounced dead and one transported to a local hospital in an unknown condition, according to the fire department.

The National Transportation Safety Board and the Federal Aviation Administration will investigate the crash, the fire department said.

The crash occurred after a vehicle collision in the area involving a Los Angeles Metro bus and a passenger vehicle earlier on Tuesday that killed at least two people.

According to several media reports, the chopper involved in the crash was a television news helicopter, one of several in area the whose crews were reporting on the bus collision.

Los Angeles Mayor Karen Bass said she was "devastated" by the loss of life, and thanked emergency responders for their swift response.

Reuters could not immediately verify whether the aircraft involved was a TV news helicopter. The Los Angeles Fire Department did not immediately respond to emailed requests for further details.