Breaking: At least three dead in LA helicopter crash near fatal bus accident

At least three people have been killed and one hospitalised after a news helicopter crashed in suburban Los Angeles while reporting on a separate fatal bus crash nearby, local authorities say.

The NBCLA media outlet has confirmed the helicopter was one of its news choppers that had been flying in the area of the San Fernando Valley while reporting on the bus crash.

Warning: This story includes graphic content some readers may find distressing.

Los Angeles Fire Department (LAFD) Captain Branden Silverman told media that authorities were still working to determine how many people may have been aboard the aircraft at the time of the incident.

He said one of the victims was a pedestrian in a car park near the helicopter crash site.

NBCLA later confirmed the other two victims were people aboard the helicopter.

Colleen Williams, an NBC4 Los Angeles anchor, confirmed during a live broadcast that the station's chopper went down just before 7pm, local time.

"We've been telling you that we've been piecing it together here. We knew it was a news chopper. We knew ‌we'd lost contact with our people out there," she said.

"We've just ⁠received the confirmation that, in fact, NewsChopper 4 went ‌down just before 7 o'clock tonight in Chatsworth.

"We are going to take a couple of minutes to think about that, process it."

Moments later their coverage abruptly cut off.

Footage from the scene in the immediate aftermath of the crash appeared to show that the wreckage of the aircraft had erupted into a fireball on the ground.

LAFD firefighters were still searching the helicopter wreckage, and authorities from the National Transportation Safety Board and Federal Aviation Administration were expected to investigate the crash, Captain Silverman said.

"First arriving unit reports an unknown make/type of helicopter has gone down between two commercial buildings," an LAFD emergency alert said.

"Fire from the crash is exposing four vehicles. Firefighters are in offensive mode, attacking the fire and assessing patients and medical triage."

A second alert later confirmed that three people had been declared dead at the scene and another was "transported to a local hospital in unknown condition".

The fire from the helicopter crash, which took dozens of firefighters to extinguish, damaged four cars and two storage containers, the LAFD alert said.

The parking lot is for a large one-story building, but the type of business was not immediately clear.

Captain Silverman described the helicopter as "pretty well destroyed" and said firefighters would need to examine the rubble to see how many victims were aboard.

He told reporters he had been at the scene of an earlier fatal accident between a bus and car when firefighters noticed a smoke column rising from the scene of the helicopter crash.

Two people were killed and six others injured in the vehicle collision which involved an SUV becoming lodged in the side of a public bus.

LA Mayor Karen Bass issued a statement to say she was "absolutely devastated by the loss of life" in the accident.

"My heart is with the families and loved ones of those we lost in the tragic bus collision and helicopter crash," she said on X.

Lindsey Horvath from the Los Angeles County Board of Supervisors described the two crashes as "a truly devastating day for Chatsworth".