A nightclub bouncer in New York was stabbed to death as he tried to enforce the city's new ban on smoking in bars, police have said.
The law was introduced to protect people from second-hand smoke
Dana Blake, 32, was attacked after ordering two men at the trendy Guernica club in East Village, Manhattan, to put out their cigarettes.
He was knifed in the lower abdomen and died in hospital following the attack in the early hours of Sunday.
Mr Blake's family has blamed his death on Mayor Michael Bloomberg's sweeping new smoking ban, which took effect in late March.
"The common person always plays the victim of these political laws and my brother was their first casualty," Anthony Blake, the victim's brother, told the New York Post.
He was quoted as saying: "I'm bitter. It's a senseless murder because of this stupid cigarette law. That's the reason this guy was killed.
It's so ironic. Something that's supposed to save lives has already taken a life
"This new rule is only going to cause more tragedy. I foresee it."
Travis Keyes, owner of the bar next to the nightclub, helped chase down two suspects as they tried to flee the scene.
He also said the argument had begun over a cigarette.
"It's so ironic. Something that's supposed to save lives has already taken a life," said Mr Keyes.
The mayor introduced the law to protect bar and restaurant workers from the effects of second-hand smoke.
HAVE YOUR SAY
Don't blame New York's law, blame the violent nature of the two arrested
Alisdair Matheson, Scotland
The health-conscious ex-smoker approved fines of $400 for establishments found to be flouting the ban.
He was confident revellers would welcome the cleaner air on a night out.
"Fundamentally, people just don't want the guy next to them smoking," he said. "People will adjust very quickly and a lot of lives will be saved."
Many club owners had opposed the ban, saying it would cost them customers and lead to public disturbances if large groups of people were forced on to the streets to smoke.
Mayor Bloomberg's spokesman called the killing "a senseless death"
A spokesman for Mr Bloomberg called the killing a "senseless death" and said the mayor's thoughts were with the family of the victim.
Two brothers, aged 29 and 31, have been arrested in connection with the attack.