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California Carjackings: Gunman Kills Four

A gunman has killed three people before taking his own life in a 25-minute shooting spree in California.

The violence started when the gunman - named by police as 20-year-old Ali Syed, an unemployed student - shot dead a woman in her 20s at her home in Ladera Ranch in the early hours of Tuesday.

He then headed north and hijacked a Dodge pickup truck in Tustin, around 40 miles southeast of Los Angeles. The driver was unhurt but a bystander was hit by gunfire and taken to hospital.

When the truck ran out of fuel, Syed stole a BMW and killed the driver, Santa Ana Police Corporal Anthony Bertagna said.

He then drove to a local business and took another small truck, killing one person and wounding another, Lieutenant Paul Garaven, of Tustin Police Department, told reporters.

Police officers followed the gunman to Orange, a city about five miles away.

As they approached Syed at a busy intersection, he got out of the vehicle and shot himself.

Police do not yet have a motive for the shootings, which came less than two weeks after former Los Angeles police officer Christopher Dorner went on the run after allegedly killing three people .

His charred remains were found inside a burned-out California mountain cabin .