Even the early-morning frenzy of people running down the street seemed routine enough for one of the city's most famous attractions.
"I thought actually there was a celebrity sighting," said Rebecca Fox, who witnessed the surging crowd on her way for coffee.
The crowd wasn't running to see a star. They were running from a shooting.
According to authorities, a man opened fire outside the building's 5th Street entrance. At least 11 people were shot -- at least one fatally -- before police killed the gunman.
At mid-morning, the man's body lay on the pavement, just feet from the entrance to the building's famous observatory, as detectives swarmed over the scene. A black bag lay next to him.
Nearby, Fox saw a woman who had been injured. A sidewalk was stained with blood, she said.
"It's just a crazy scene," she said.
CNN iReporter Ashwin Purushan stumbled across the scene on this way to work.
"There was a sense of panic and mass confusion," he said.
Police closed down the streets near the Empire State Building, which attracts 3.6 million visitors a year. Crowds of onlookers crowded up to police barricades, chattering about the shooting, CNN iReporter Kelly Wilson said.
Another iReporter, Vladimir Dusio, who lives across the street from the building and said the normally busy block in front of his building looked very different in the wake of the shooting.
"I don't see any pedestrians around our building at all, I just see cops," he said.
While authorities say the shooting was not related to terrorism, the fear of such violence wasn't far from the minds of some people who live and work nearby, witnesses said
For some, the shootings dredged up memories of the September 11, 2001 terrorist attack that toppled the twin towers of the World Trade Center and left the Empire State Building as New York's tallest building.
"For us it one of the worst nightmares to be subjected to something like this and because the Empire State Building is such an iconic building, and there is so much traffic there you always wonder if someone is going to do something there," Dusio said. "It is very unsettling."
CNN's Rose Arce contributed to this report.