The gunshots rang out on the Fifth Avenue side of the building around 9 a.m., when pedestrians on their way to work packed sidewalks and merchants were opening their shops.
"People were yelling 'Get down! Get down!'" said Marc Engel, an accountant who was on a bus in the area when he heard the shots. "It took about 15 seconds, a lot of pop, pop, pop, pop, one shot after the other."
Afterward, he saw the sidewalks littered with the wounded, including one person "dripping enough blood to leave a stream."
Wearing an olive suit and tie and carrying a briefcase, Jeffrey Johnson walked up to the import company vice president, Steven Ercolino, put a gun to his head and fired without saying a word, authorities said. A witness told investigators that Johnson shot Ercolino once in the head and, after he fell to the sidewalk, stood over him and shot him four more times.
"Jeffrey just came from behind two cars, pulled out his gun, put it up to Steve's head and shot him," said Carol Timan, whose daughter, Irene, was walking to Hazan Imports at the time with Ercolino.
The gunman walked away and calmly turned up 5th Avenue, where he blended in with the crowd, police said.
A construction worker who saw the shooting followed Johnson and alerted two police officers, a detail regularly assigned to patrol city landmarks like the 1,454-foot (443-meter) skyscraper since the 9/11 terror attacks, officials said.
Police released dramatic surveillance video that showed the confrontation lasted only a few seconds. Johnson was walking rapidly down the street trailed by two police officers when he stopped, wheeled around and pulled out a gun.
About a dozen people ran for their lives, including two small children who were just feet away from Johnson. He pointed the gun at the officers, who quickly fired at him.
Johnson dropped his briefcase, fell to his knees and then collapsed on the ground.
The bystanders likely were hit by police officers' stray gunfire, some of it bullets that rebounded off planters in front of the skyscraper and grazed pedestrians. The two officers fired 16 shots.
The wounded victims were five women and four men, authorities said. All were from New York City, except a woman from Chapel Hill, North Carolina. They suffered graze wounds or other minor injuries.
Police said six of them were treated at a hospital and were released by Friday night. The three others were being treated for non-life-threatening injuries.
The surveillance video shows Johnson pointing his weapon at police, but it's likely he did not get a chance to fire, investigators said.
A witness had told police that Johnson fired at the officers, but authorities say ballistics evidence so far doesn't support that. Johnson's .45-caliber weapon held seven rounds, they said. He fired five times at Ercolino, one round was still in the gun and one was ejected when officers secured it, authorities said.
Kelly said the officers who caught up to Johnson had "a gun right in their face" and "responded quickly, and they responded appropriately."
"These officers, having looked at the tape myself, had absolutely no choice," Kelly said.
Kelly said investigators believe police may be responsible for some of the injuries, based on the gunman's weapon. Johnson's semi-automatic weapon was equipped to fire at least eight rounds; at least one round was left in the clip, police said. Another loaded magazine was in his briefcase.
Johnson legally bought the gun in Sarasota, Florida, in 1991, but he didn't have a required permit to possess the weapon in New York City, police said.
"New York City, as you know, is the safest big city in the country, and we are on pace to have a record low number of murders this year," Mayor Michael Bloomberg said. "But we are not immune to the national problem of gun violence," he said about the shooting, which comes in the wake of mass shootings inside a Colorado movie theater and a Sikh temple in Wisconsin.
Robert Asika, who was shot in the right arm, said he was "100 percent positive" that a police officer had shot him. He also said he saw Johnson fire his gun at the officers.
Asika, 23, sells tickets for the Empire State Building's observatory.
"When I woke up this morning, I didn't even want to go to work," he said. "Something told me not to go to work."
The wounded victims were five women and four men, aged 20 to 56, authorities said. All were from New York City, except a 35-year-old woman from North Carolina. They suffered graze wounds or other minor injuries, and police believe that at least some of the injuries were caused by bullet fragments that ricocheted off security planters.
Johnson, 58, and Ercolino had traded accusations of harassment when Johnson worked there, Kelly said. Johnson had been laid off about a year ago. Police said he blamed the victim, believing Ercolino had failed to aggressively promote his line of women's T-shirts.
Ercolino's profile on the business networking site LinkedIn identified him as a vice president of sales at Hazan Import. It said he was a graduate of the State University of New York at Oneonta.
He was single and had recently moved to New Jersey after living for a time in Warwick, just north of New York City, said his eldest brother, Paul Ercolino. He grew up in Nanuet, New York.
"He was in the prime of his life," Paul Ercolino said, adding that the family was in shock. He said his brother was a gregarious salesman - known to nieces and nephews as "Uncle Ducky" because of his nearly blond hair - who had followed his father into the garment industry, then later worked in women's handbags and accessories.
He never mentioned to the family that he had any problems with a co-worker, Paul Ercolino said.
Hazan Import Corp. imports women's clothing and accessories, according to public records. Calls to its executives weren't immediately returned
Johnson worked at the company near the Empire State Building for about six years and was laid off because of downsizing, Kelly said.
Even after he was laid off, Johnson would leave left his Upper East Side apartment building each morning in a suit, and often returned about a half hour later after going to get breakfast at McDonald's, his neighbors said.
"He was always alone," said Gisela Casella, who lived a few floors above him. "I always felt bad. I said, 'Doesn't he have a girlfriend?' I never saw him with anybody."
His superintendent, Guillermo Suarez, said he lived alone in a one-bedroom apartment that he was subletting. He called him a "very likable guy," who always wore a suit.
Metal detectors and bag searchers have been standard at the Empire State Building since 1997, when a gunman opened fire on the 86th floor observation deck of the 102-story skyscraper, killing one tourist and wounding six others before fatally shooting himself.
A guard at the Empire State Building said the shooting didn't involve the parts of the building where tourists gather to visit the skyscraper.
Millions of tourists ascend the building's heights to gape over the city from its observation deck.
The skyscraper and its observatories remained open throughout the mayhem Friday, the building's owner said.
"This unfortunate event had nothing to do with the Empire State Building and with terrorism," said Anthony Malkin of Malkin Holdings.