A man seen bloodied and limping as he was led away by police in handcuffs has been arrested on suspicion of killing 10 people, including a police officer, at a Colorado grocery store, marking America's second fatal mass shooting in a week.
The gunman, who was not publicly identified, opened fire at a King Soopers outlet in Boulder, about 28 miles (45 km) northwest of Denver, in the late afternoon on Monday, sending panicky shoppers and employees scurrying for cover as hundreds of police officers converged on the area.
Media reports said the suspect, who police said was believed to have acted alone, was armed with a rifle.
Authorities gave few details and offered no possible motive for the bloodshed, which came six days after a gunman went on a killing spree in the Atlanta area, shooting eight people to death at three-day spas before he was arrested.
Like those shootings, Monday's violence in Colorado unfolded in a place of business at the hands of a single armed assailant.
"We were at the checkout, and shots just started going off," said Sarah Moonshadow, 42, a shopper who was in the store with her adult son, Nicholas, when the gunfire began.
"And I said, 'Nicholas get down.' And Nicholas ducked. And we just started listening and there, just repetitive shots ... and I just said, 'Nicholas, run.'"
Moonshadow said she tried to attend to a victim she saw lying on the pavement just outside the store, but her son pulled her away, telling her, 'We have to go.'" The woman broke down in sobs recounting their ordeal, adding, "I couldn't help anybody."
Boulder Police Chief Maris Herold, her voice choking with emotion, said 10 people perished at the scene. Among them was 51-year-old officer Eric Talley, an 11-year veteran of the Boulder police force, who Herold said was the first to arrive at the store. Talley had seven children, and had been looking for a less dangerous job, according to his father.
Police said the accused gunman was taken to a hospital for treatment of injuries he sustained in the violence but did not explain how he was hurt. There was no word on when he might face an initial court appearance.
Video footage broadcast by television stations showed a shirtless, bearded man in boxer shorts being led away from the store limping and in handcuffs, before he was placed on a stretcher and loaded into an ambulance. One of his legs appeared covered in blood.
The killings added to a long line of mass shootings in Colorado accounting for some of the most shocking episodes of gun violence in modern U.S. history.
In 2012, a young man dressed in tactical gear burst into a movie theater in the Denver suburb of Aurora during a midnight screening and sprayed the audience with gunfire, killing 12 and wounding 70. In 1999, a pair of students went on a shooting rampage at Columbine High School near Littleton, Colorado, murdering 12 classmates and a teacher before taking their own lives.
Video captured by an onlooker, apparently while the shooting was still in progress, was posted to social media and aired on TV stations. It showed two bodies lying in the grocery store parking lot, before the person with the camera walks inside and films a third body, as three shots are heard in the background.
The United Food and Commercial Workers International Union, Local 7, which represents 32 employees at the King Soopers outlet, credited some of the grocery workers with helping customers escape through a rear exit.
It also thanked customers and emergency responders who "acted swiftly to prevent even greater loss of life."
The shooting occurred about 2 miles from the flagship campus of the University of Colorado, in the Table Mesa area of the city that is home to a residential neighborhood and the hilltop laboratory of the National Center for Atmospheric Research.
