California authorities have declared a mass casualty alert in Huntington Beach following a helicopter crash this afternoon. According to preliminary reports from local emergency services, the incident claimed the lives of several people on board and resulted in injuries to bystanders on the ground.

Witnesses reported that the car suddenly lost control in the air and crashed into trees near the coastal area.

"The helicopter spun out of control and crashed right on top of the people," — one of the eyewitnesses described the incident in a local media report.

Rescue teams quickly arrived at the scene, where they are clearing the blockade and providing assistance to the victims.

The Federal Aviation Administration (FAA) and the National Transportation Safety Board (NTSB) have launched an investigation into the cause of the accident. Details regarding the number of fatalities are being clarified, but the situation remains tense, with traffic restrictions in the area.