A violent rampage that left four dead began in the pre-dawn hours on Tuesday when a 20-year-old killed a woman in his southern California home and sped away in his parents' car, authorities said.
An hour later, it was over — but not before Ali Syed had killed two more people during carjackings, shot up vehicles on a busy freeway interchange and left three others injured in a trail of carnage that stretched across 25 miles (40 kilometers) in suburban Orange County.
One driver was forced from his BMW at a stop sign, marched to a curb and shot in the back of the head as other commuters watched in horror.
"He was basically executed," Santa Ana police Cpl. Anthony Bertagna said. "There were at least six witnesses."
Syed later killed himself. He lived with his parents at a residence where the first victim, an unidentified woman in her 20s, was slain, Tustin police Chief Scott Jordan said. He was unemployed, taking one class at a local community college, Jordan said.
The woman was not related to the shooter and it wasn't 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 the residence when shots were fired, and reported it, he said.
Jordan said Syed stated to one carjacking victim: "I don't want to hurt you. I killed somebody. Today is my last day."
The killings happened not long after a bloody saga that gripped Southern California for six days, as former Los Angeles police officer Christopher Dorner eluded a massive manhunt after killing three people.
Dorner died Feb. 12 from an apparent self-inflicted gunshot wound to the head after a fiery gun battle that left one police officer dead.
Americans have been embroiled in a fierce debate over gun violence, as the Obama administration wages an uphill battle to get Congress to approve new gun control laws, including a ban on military-style assault weapons like the one used in a Connecticut elementary school shooting that left 20 children dead in December.
The proposals would not ban the type of shotgun apparently used in Tuesday's shooting spree.
Vice president Joe Biden sought to reassure Americans of that on Tuesday as he pushed the government's case in an online video as part of a Facebook town hall hosted by Parents Magazine.
He said he himself keeps two shotguns and shells locked up at home but insisted that nobody needs an assault rifle for protection.
He said banning such high-powered weapons would not amount to an infringement on the Second Amendment of the Constitution, which guarantees citizens the right to bear arms.
Jordan said there was no indication of a motive in Tuesday's shootings, but he sought to assure residents that the violence was over.
The violence began early Tuesday morning, when deputies responded to a call from Ladera Ranch, a sleepy inland town about 55 miles (88 kilometers) southeast of Los Angeles. They found the woman shot multiple times.
From Ladera Ranch, police said the gunman headed north and pulled off a highway in Tustin, about 20 miles (12 mile) away, with a flat tire and other damage to his parents' car.
A man who was waiting in a shopping center parking lot to carpool with his son saw Syed had a gun and tried to escape in his Cadillac, Jordan said. Syed ran after the car as it drove away and fired his shotgun through the back window, striking the driver in head but not killing him.
Syed then crossed the street to a gas station, where he approached the driver of a pick-up and asked for his keys, Jordan said.
"He says something to the effect of, 'I've killed somebody. Today's my last day. I don't want to hurt you. Give me your keys,'" he said. "He hands over the keys and he gets in the truck and leaves."
Syed got back on the freeway, where he pulled to the side of the road and began firing at commuters, Jordan said.
One driver was struck in the mouth and hands. He didn't have a cellphone, but was able to drive home and call police. Two other cars were hit but their drivers weren't injured, Jordan said.
"All of this is happening so quickly," he said, estimating that Syed shot at drivers from the side of the freeway transition for about a minute.
The shooter then exited the freeway in nearby Santa Ana but ran the curb and got his car stuck, authorities said.
He approached Melvin Edwards, 69, who was on his way to his Santa Ana business, as Edwards sat in his BMW at a stop sign. Syed forced Edwards to get out of his car, marched him across the street and shot him three times, including in the back of the head and the back, as horrified drivers looked on, Jordan said.
Syed took Edwards' BMW and next popped up at a business where he shot and killed construction worker Jeremy Lewis, 26. Lewis' co-worker rushed to intervene
and was shot in the arm, Jordan said.
Syed took the second construction worker's utility truck and fled to Orange, this time with California Highway Patrol officers in pursuit. He jumped from the moving utility truck at an intersection, and shot himself immediately, Jordan said.
A shotgun was recovered at the scene.
A message left at Syed's parents' home wasn't immediately returned on Tuesday.