Minutes later, Johnson was dead in front of the landmark skyscraper, killed by police Friday in a chaotic confrontation that sent bullets ricocheting, wounded nine other people and left sidewalks near one of the world's best-known landmarks spattered with blood.
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 surveillance video shows Johnson pointing his weapon at police, but it's likely he did not get a chance to fire, investigators said.
Startled New Yorkers looked up from their morning routines in the crowded business district to see people sprawled in the streets bleeding and a tarp covering the body in front of the tourist landmark.
"I was on the bus and people were yelling 'get down, get down," said accountant Marc Engel. "I was thinking, 'You people are crazy, no one is shooting in the middle of midtown Manhattan at 9 o'clock in the morning."
It was over in seconds, he said — "a lot of pop, pop, pop, pop, one shot after the other." Afterwards he saw sidewalks littered with the wounded, including one man "dripping enough blood to leave a stream."
Johnson, who neighbours had seen leave his apartment in a suit every day since he was laid off a year ago, had worked for six years for Hazan Imports and was let go when the company downsized, police Commissioner Ray Kelly said.
Police were looking into his relationship with the victim, Steven Ercolino, the company's vice-president of sales, who had traded accusations of harassment with Johnson when he worked there. Johnson, 58, also blamed Ercolino for his layoff, saying that he hadn't aggressively marketed Johnson's new T-shirt line, police spokesman Paul Browne said.
After waiting for Ercolino, 41, to come to work, Johnson walked up to him, pulled out a .45-calibre pistol and fired at his head, Kelly said. After he fell to the ground, Johnson stood over him and shot four more times, a witness told investigators.
"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.
A construction worker who saw the shooting followed Johnson and alerted two police officers, a detail regularly assigned to patrol city landmarks such as the 1,454-foot skyscraper since the Sept. 11 terror attacks, officials 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.
A witness had told police that Johnson fired at the officers, but authorities say ballistics evidence doesn't support that. Johnson's 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.
Another loaded magazine was found in Johnson's briefcase.
Johnson legally bought the gun in Sarasota, Fla., 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 of the shooting, following mass shootings a Colorado movie theatre and a Sikh temple in Wisconsin.
Robert Asika, who was shot in the right arm, said he was "100 per cent positive" that a police officer had shot him. 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, authorities said. All were from New York City, except a woman from Chapel Hill, N.C. They suffered graze wounds or other minor injuries.
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 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.
"He was in the prime of his life," Paul Ercolino 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
Even after he was laid off, Johnson would leave 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 neighbours 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."
Internet records list him as administrator of the website for a business called St. Jolly's Art, which sold iron-on art for T-shirts, including stylized drawings of fighter planes, muscle cars and ships.
Johnson was also part of a community of bird watchers and photographers who document hawks and other wildlife living in Central Park, a few blocks from his home. In an email to another bird watcher, who works at The Associated Press, Johnson wrote tenderly about spending a winter night watching ducks in the park.
"Near midnight by the Harlem Meer I watched a little 'flotilla' of Mallards swimming and softly honking ...fifteen degree temp and they were carrying on unfazed. Just remarkable," he wrote.
Gunshots so close to one of the city's leading tourist attractions immediately prompted fears of terrorism, but federal officials said that wasn't the case, and a guard at the skyscraper said it didn't involve the parts of the building where tourists gather to visit the skyscraper.
Metal detectors and bag searchers have been standard at the 102-story skyscraper since 1997, when a gunman opened fire on the 86th floor observation deck of the Empire State Building, killing one tourist and wounding six others before fatally shooting himself.
The skyscraper remained open Friday throughout the mayhem, although the tourist attraction's workers became witnesses.
"We were just working here and we just heard bang, bang, bang!" said Mohammed Bachchu, a worker at a nearby souvenir shop.
He said he rushed from the building and saw seven people lying on the ground, covered in blood.
Queens resident Rebecca Fox said she saw people running down the street and initially thought it was a celebrity sighting but then saw a woman shot in the foot and a man dead on the ground.
"I was scared and shocked and literally shaking," she said.
She said police seemed to appear in seconds.
"It was like 'CSI,'" she said, "but it was real."
Contributing to this report from New York were Alex Katz, Samantha Gross, Julie Walker, David B. Caruso, Adam Geller, Karen Matthews, Ula Ilnytzky, Anne D'Innocenzio and Meghan Barr.