A YouTube video thought to be linked to the shootings in California sees a young man claiming he will get "retribution" for a lack of interest shown in him by women.
The footage shows a young man complaining that it is "unfair" that he is still a virgin before threatening a mass slaughter of college students and Isla Vista residents.
"It's obviously the work of a madman," the sheriff said of the shooting. "There's going to be a lot more information that will come out that will give a clearer picture of just how disturbed this individual was."
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Detectives in Westminster are investigating after the man was discovered on the Route 189 bus in Marylebone shortly after midnight.
The murderer was shaking and appeared to be gasping for air for around 13 minutes before dying.
The positive results come after Chancellor Philip Hammond admitted the government is prepared to sell its stake at a loss to the taxpayer.