NEW YORK – A laid-off clothing designer fatally shot an executive at his former company outside the Empire State Building on Friday, setting off a chaotic showdown with police in front of one of the world’s best-known landmarks. Officers killed the gunman and at least nine others suffered minor wounds, likely all of them by stray police gunfire, authorities said.

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 sidewalks littered with the wounded.

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 Fifth 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 skyscraper since the 9/11 terror attacks, officials said.

The two officers drew their weapons and fired 16 rounds, killing Johnson, Police Commissioner Raymond Kelly 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.

“These officers … had absolutely no choice,” Kelly said. “This individual took a gun out very close to them and perhaps fired at them.”

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.”

Robert Asika, who was shot in the right arm, said he was “100 percent 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, aged 20 to 56, authorities said. All were from New York City, except a 35-year-old woman from Chapel Hill, N.C.

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 aat Hazan Import Corp., 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.

Hazan Import Corp. imports women’s clothing and accessories, according to public records. Johnson worked at the company for about six years and was laid off because of downsizing, Kelly said.

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 neighbors said.

A guard at the skyscraper said the shooting didn’t involve the parts of the building where tourists gather. 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.

Millions of tourists ascend its heights to gaze at the city from its observation deck, made famous in films such as “Sleepless in Seattle.” It was 1933’s “King Kong” that showed a giant ape clutching Fay Wray and fending off airplanes atop the tower.