A violent rampage that left four dead began before dawn on Tuesday when a 20-year-old killed a woman in his southern California home and sped away in his parents' car.
An hour later, it was over - but not before Ali Syed had killed two more people during car-jackings, shot up vehicles on a busy highway and left three others injured in a trail of carnage that stretched across 25 miles in suburban Orange County.
A driver, Melvin Edwards, 69, was forced from his BMW at a stop sign, marched to a kerb and shot in the back of the head as other commuters watched in horror. "He was basically executed," Santa Ana policeman Anthony Bertagna said. "There were at least six witnesses."
Syed later killed himself. He lived with his parents at a property where the first victim, an unidentified woman in her 20s, died, Tustin police chief Scott Jordan said.
He said that Syed was unemployed, taking one class at a local community college.
The woman was not related to the gunman and it was not known what she was doing at the home, said Orange County sheriff's spokesman Jim Amormino.
Syed's parents were in the house at the time, fled when shots were fired, and reported it, he said.
Mr Jordan said Syed told one carjacking victim: "I don't want to hurt you. I killed somebody. Today is my last day."
He said there was no indication of a motive for the shootings, but he sought to assure residents that the violence was over.