Police in Los Angeles are trying to determine what prompted a man to shoot his grandmother and injure another woman before holding dozens of people hostage in a busy supermarket amid a tense standoff with armed officers.
A woman was shot and killed when the gunman ran into the Trader Joe's store in Silver Lake on Saturday, but no hostages were seriously hurt before the man handcuffed himself and surrendered about three hours later.
The man shot his grandmother seven times and wounded another woman, who he forced into a car, police said. Officers tracked the car, gave chase and exchanged gunfire with the man, who crashed into a pole outside the supermarket and then ran inside.
The man's grandmother is in hospital in a critical condition, while the woman he forced into a car suffered minor injuries.
Frightened customers and workers dived for cover as police bullets fired at the man shattered the store's glass doors.
Some people inside the supermarket climbed out windows, and others barricaded themselves in rooms as scores of police officers and firefighters and 18 ambulances converged on the scene and prepared for mass casualties.
Heavily armed officers in riot gear stood along the side of the store and used mirrors to look inside as hostage negotiators tried to coax the man into freeing his 40-50 hostages and surrendering.
At about 6.30pm local time, the man agreed to handcuff himself and walked out the front door, surrounded by four of the hostages. The unidentified man was immediately taken into custody.
Mayor Eric Garcetti congratulated police and firefighters for their work, adding: "The heroism that was shown today was second to none, and the teams that were able to respond, secure the perimeter and engage in conversation with the suspect no doubt saved lives today," he said.
Police Chief Michel Moore said the gunman made a "series of demands" during the standoff but crisis negotiators believed they could persuade him to surrender peacefully.
Investigators are not sure what led to the initial violence that produced the car chase and standoff. Mr Moore said at about 1.30pm, the suspect shot his grandmother and another woman in a South Los Angeles home and then forced the other woman into his grandmother's car.
Officers tracked the car using a stolen-vehicle tracking system and tried to stop the man in Hollywood, but he refused to pull over. During the chase, the man fired at officers, shooting out the back window of his car.
Outside the store, the man exchanged gunfire with police again and a woman was shot and killed. It is unclear if she died from police gunfire or was killed by the gunman.
Fire officials said six people, ranging in age from 12 to 81, were taken to hospital. None had been shot, and all were in fair condition.
Among those caught up in the incident was 91-year-old Don Kohles, who was walking into the supermarket when he saw "two police cars coming like a bat out of hell" and the man crashed into the pole.
The driver got out, and police started firing at him as he ran towards the supermarket. Mr Kohles said he hurried inside, and he and others took cover as the man ran in.
"Those bullets went right over the back of me as he was running right down the main aisle," Mr Kohles said.
Christian Dunlop was on a corner near the store when he saw four people run out. One person, an employee, was dragging an injured woman by the hands. "She appeared lifeless," Mr Dunlop said.
He then saw about five employees hang out a second-floor window and drop to the ground and about 15 other people run to safety from the back of the store. Among them was a police officer carrying a small child, he said.
"I know all the employees," Mr Dunlop said. "I see them all the time. My heart was just racing and thinking about all the endless possibilities."