Helicopter - HEMS B407 down - Curt Lewis

Four People Killed In Medical Helicopter Crash in California

Four people have been killed after a medevac helicopter crashed in Kern County, California.

Just before 7 p.m. Thursday the Skylife H-4 helicopter left Porterville Airport with a critical patient who was being transferred to San Joaquin Community Hospital in Bakersfield.

Ten minutes into the flight when a routine safety call from the Fresno County EMS dispatch center was unable to make radio contact with Skylife, they immediately contacted both airport towers.

Dispatch then contacted the local fire department and sheriff's office.

The helicopter has one pilot, a flight nurse, flight paramedic and the patient.

An Air Ambulance spokesperson told the media at a press conference they were thankful for the support they've been receiving from officials and they do know the identities of the deceased and are in the process of contacting the families."

"We don't know exactly what the cause of the crash was at this point." Air Ambulance told reporters.

The National Transportation Safety Board (NTSB) have confirmed to ABC News that they are investigating the crash.