A brief surveillance video released Friday night by police shows the man walking behind a large planter on a busy street. He appears to point something as two officers approach, coming to within a few feet of him. Then, as bystanders run in all directions, the man falls abruptly to the ground after apparently being shot.
Witnesses said police shot Johnson at least three times.
"I heard the gunshots," said Anika Basu, who was on a bus near the building when the shooting happened. "I looked toward the left and saw three people fall. ... The whole entire crosswalk emptied and people were running.
Police say Johnson used a semiautomatic handgun and was carrying extra ammunition in his briefcase. He purchased the weapon legally in 1991 in Florida but did not have a permit to carry it in New York City.
The former Manhattan resident did not appear to have had a criminal record, but authorities were still checking, Mayor Michael Bloomberg said.
Johnson's neighbor, Gisela Casella, described him as a quiet animal lover whose death left her "shocked."
"He was the nicest guy. He must have snapped or something. I don't know," she said.
His landlord, Guillermo Suarez, said he lived alone and that he'd seen Johnson leave the building around 8 a.m. in a suit.
By around 9 a.m., the shootings had prompted local and federal authorities to close several streets around Fifth Avenue and West 34th Street, snarling traffic in the heart of Manhattan.
The Empire State Building is one of the most famous skyscrapers in the world and one of New York's best-known tourist attractions.
Each year, about 4 million people visit the building's two observation decks. At more than 1,453 feet tall, the landmark building reaches more than a quarter-mile into the sky.