Bystanders in New York whipped out cellphones to film the shooting by police of a man allegedly threatening them with a knife in the tourism magnet of Times Square.
Saturday's confrontation between the man and police was all caught by passersby, who, although apparently horrified, ran to get a better look - until the encounter ended in a hail of bullets.
One film of the incident posted on NBC television's website shows the suspect, wearing a white shirt, backing away from a large number of police, while bystanders yelled and tried to keep pace.
Suddenly, a volley of about a dozen shots rang out, prompting shrieks and shouting in the crowd.
The New York Times website ran a photograph taken by a Brazilian tourist, Lincoln Rocha, in which two officers draw their weapons and point them at the man carrying what appeared to be a knife.
A video on the Times site taken by another tourist shows the man running backward from police. A bystander can be heard warning him to lie down, shouting: "They're going to shoot you bro!"
Other bystanders can be seen sprinting and holding up their cameras over their heads to get better angles of the drama.
Police said the man threatened them, refused to surrender and that officers were unable to subdue him with pepper spray. When he lunged at police, they fired 12 shots, NBC reported, killing him.
The New York Daily News quoted relatives of the slain man Sunday saying that excessive force was used. "It doesn't take 12 bullets to kill one person," the dead man's aunt, Margaret Johnson, told the newspaper. "I think it could have been done another way."
However, NYPD Commissioner Raymond Kelly was quoted by local media as saying that police "responded appropriately."
Times Square is the site of the New Year's Eve countdown party and is in the heart of Manhattan's theater district.