Police in California say one female suspect has been found dead after opening fire at YouTube's US headquarters, while four people are in hospital.

The shooting was reported at 8am today, at the company headquarters in San Bruno, California.

Police said the woman believed to be the shooter is dead of what appeared to be a self‑inflicted gunshot.

San Bruno Police Chief Ed Barberini told reporters that authorities found a victim with a gunshot wound toward the front of the business when they arrived. Several minutes later, they found the female shooter.

The Los Angles Times has reported that so far authorities do not believe this was an act of terrorism and appears instead to have been a case of domestic or workplace violence ‑ although the investigation has just begun.