A recently laid-off store worker shot a former colleague to death Friday morning outside New York's iconic Empire State Building and then randomly opened fired on people nearby before being killed in an exchange of fire with police, police said.

The shooting set off chaos in the heart of Manhattan at the height of the summer travel season and just after the morning rush hour. Police on their regular anti-terrorism duties in the highly touristed area rushed to the scene.

Police said nine others were hit by gunfire, but all were expected to survive.

Mayor Michael Bloomberg said some of the victims may have been hit by police bullets as police and the gunman exchanged fire.

"This was a terrible tragedy," Bloomberg told a press conference. "We are not immune to the national problem of gun violence."

Police identified the gunman as Jeffrey Johnson, 53, but they said they had little details yet about his background, including a criminal record.

Police Commissioner Ray Kelly said Johnson had worked as a designer of women's accessories before being laid off last year. Kelly said Johnson fired at the former colleague three times at close range after a dispute. The name of the 41-year-old victim was not released pending notification of the family.

Federal officials said the 9 a.m. (1300 GMT) shooting wasn't related to terrorism.

Construction worker Chris Ogden told the Daily News tabloid he was working on a scaffold above one entrance to the building when he saw someone in a suit and carrying a briefcase start shooting.

"He shot the guy in the head," Ogden told the newspaper. "The guy went down. He took a second shot when he was down."

Ogden said then casually walked away. "We were screaming from the top, `It's the guy in the grey suit!'" Ogden said.

Aliyah Imam told Fox 5 News television she was standing at a red light when a woman standing next to her fell to the ground. She said the woman was hit in the hip.

The gunman was "shooting indiscriminately at people," Imam said.

Resident Rebecca Fox, 27, said she saw people running down the street and at first thought it was a celebrity sighting. Then she saw a woman shot in the foot and a man dead on the ground.

"I was scared and shocked and literally shaking," she said.

A photo posted to an Instagram account belonging to a person identified as mr_mookie, an eyewitness, shows a victim, his head propped on the sidewalk and his body in the street, being helped by bystanders. The victim's identity and condition were not immediately known.

A body remained at the scene more than an hour after the shooting. Police scoured the area for bullets.

The Empire State Building anchors one of the city's busiest areas. The website for the building says about four million people visit the tower's observatory decks each year, and sidewalks outside the building bustle with people selling tickets for its attractions.

Many others are shoppers drawn to stores along both 34th Street and Fifth Avenue. The shooting occurred at their intersection. Streets around the immediate area remained closed at midday.