The typical afternoon furor in Times Square became something more menacing on Saturday as throngs of police officers drew their weapons and pursued a man with a large knife down Seventh Avenue and then shot him to death.

The scene was chaotic, confusing and almost certainly dangerous. Yet many bystanders stopped to watch, record video and take photos.

Lincoln Rocha, 28, and his wife, Priscilla Rocha, 28, were visiting New York City from Brazil. While walking down Seventh Avenue, they noticed three police officers talking to a man on the sidewalk. The man pulled out a knife, and the officers pulled out their guns.

“And that’s when I started taking photos,” Mr. Rocha said.

Lincoln Rocha

Other visitors and New York residents joined in, including Jeffrey Gibson, 39, of Richville, N.Y., whose video captured the pursuit, along with a frighteningly prescient warning shouted by another bystander: “They’re going to shoot you, boy.”

Julian Miller, 22, who was visiting New York from Boston, said the police confiscated his phone after he recorded video of the confrontation. He said in an interview that he followed the pursuit from Times Square to 37th Street and Seventh Avenue, his phone recording as he ran to keep up. He said a police detective pulled him aside after the shooting and asked to see his phone and the video.

“His eyes got big when he saw the video,” Mr. Miller said, adding that he had captured the shooting on video. “He went to go show his boss, and then they took my phone away.” He said the officer told him not to speak with the news media.

What happened in the moments leading up to the shooting was not precisely clear. Among the clearest videos made public was one provided by a witness to NBC News.

In it, the suspect is seen walking backward along the sidewalk, passing a Chipotle restaurant. The police later said he was carrying a knife with a six-inch blade. The video is shaky and shot from across the street from the police and the suspect. At one point, several officers appear to crowd around the man, who is hidden from view. Then shots ring out.

The authorities said that the man lunged at the police with what appeared in a police photo to be an Ikea kitchen knife, prompting two officers to open fire. Questions about whether the shooting was justified were immediately raised on Twitter, with equal measures of praise and condemnation for the New York Police Department.

Wow. Well done NYPD. That part of NYC is crazy on weekends. Cop fatally shoot knife-wielding man in Times Square //t.co/C8Z4jJ0i — The_Steffer (@The_Steffer) 11 Aug 12

That guy that the NYPD killed in times square today earned that. Totally justified. Still crazy though! #wow — Ty (@tyboogy101) 11 Aug 12

Others were more critical of the police, questioning why such force was required.

Open fire on a man carrying a knife in TIMES SQUARE? What happened 2 shooting 2 DISABLE? Bust a knee-cap so he can’t run. — ThatWritingChic (@thatwritingchic) 11 Aug 12