The "knockout" game that left two Syracuse men dead has been gaining national attention as teens in other cities beat random victims.

Teens playing knockout killed Michael Daniels, 51, in May. James Gifford, 70, was killed in September. It's possible teens were playing "knockout" then, too.

Authorities across the country say they have seen an increase in deaths and assaults where teens are playing "knockout."

Earlier this week, the deadly game was featured in a segment on CBS This Morning.

In each case, police are investigating whether the attacks are part of a violent game called "knockout," where the object is to target unsuspecting pedestrians with the intention of knocking them out cold with one punch.

Authorities and psychologists say the concept has been around for decades -- or longer -- and it's played mostly by impulsive teenage boys looking to impress their friends.

In the Syracuse case of Daniels, he was beaten and stomped to death in May outside Los Amigos Market.

A 16-year-old was found guilty of manslaughter, and his 13-year-old co-defendant pleaded guilty to assault, admitting he started the fatal beating by trying to knock out Daniels with a single punch

Both were sentenced to 18 months behind bars.

Gifford, the other Syracuse case, died after being attacked in September. Described as a gentle man, he was coming out of the Elmwood 7-11 that morning when he was attacked.

Romeo Williams, 18, of Solvay, has been charged with first-degree manslaughter and is awaiting trial.

In New York, a 78-year-old woman strolling in her neighborhood was punched in the head by a stranger and tumbled to the ground. In Washington, a 32-year-old woman was swarmed by teenagers on bikes, and one clocked her in the face. In Jersey City, a 46-year-old man died after someone sucker-punched him and he struck his head on an iron fence.

"It's hard to excuse this behavior, there's no purpose to this," said Jeffrey Butts, a psychologist specializing in juvenile delinquency at the John Jay College of Criminal Justice. "When someone runs into a store and demands money, you can sort of understand why they're doing it, desperation, whatever. But just hitting someone for the sheer thrill of seeing if you can knock someone out is just childish."

New York City police have deployed additional officers to city neighborhoods where at least seven attacks occurred in the past few weeks, including the assault on the 78-year-old woman.

Police Commissioner Raymond Kelly said some are smacked, some are more seriously assaulted, and some harassed. The department's hate crimes task force is investigating, because some attacks have been against Orthodox Jews in Brooklyn.

In Washington, D.C., police were investigating two assaults in the past week, both of which resulted in minor injuries but not unconsciousness.

One victim, Phoebe Connolly, of Brattleboro, Vt., said she was randomly punched in the face by a teenager while riding her bike during a work-related visit to Washington last Friday. Connolly, who is 32 and works with teenagers in her job, said the blow knocked her head to the side and bloodied her nose.

"I don't know what the goal was," she said. "There wasn't any attempt to take anything from me."

While some of those attacked have been white, and some suspected attackers black, experts said the incidents are more about preying on the seemingly helpless than race or religion.

"It's about someone who is seemingly helpless, and choosing that person to target," Butts said.

A recent media blitz about the game circulating on television stations and online isn't helping, Connolly and experts said, especially because images are being repeatedly broadcast of victims in a dead fall, smacking the ground with a limp thud.

The viral footage comes from older incidents: In one instance from 2012, 50-year-old Pittsburgh English teacher James Addlespurger was punched in the face and falls to the curb. The image was caught on surveillance cameras, and a 15-year-old was arrested.

"The behavior of the sudden assault of someone who seems helpless has appealed to the idiotic impulsive quality of adolescence forever," said Butts. "But there are now bragging rights beyond your immediate circle, when this is on television and online."

Paul Boxer, a psychology professor at Rutgers University who studies aggressive behavior, said Thursday the media stories may perpetuate the assaults, but most teens clearly aren't unfeeling sociopaths.

"You've got some impressionable kids, already with a propensity for violence who could be affected by this," he said. "But not because they are hoping to hurt somebody, it's more about risk taking, and new, different and exciting ways of getting into trouble."

In Lower Merion, a leafy suburb near Philadelphia, two attacks may be related to the game.

"We do worry that it's something like that ... because we've had two similar assaults, neither one of which resulted in a robbery," said Lt. Frank Higgins of the Lower Merion Township Police Department.

In one, two 19-year-olds were charged with knocking down a 63-year-old man out walking his dog the evening of Oct. 29. They were arrested nearby a short time later, and have been charged with assault, Higgins said. No arrests were made in the other incident from September.

Also in September in Jersey City, N.J., two 13-year-olds and a 14-year-old were charged as juveniles in the murder of 46-year-old Ralph Eric Santiago. He was found Sept. 10 with his neck broken and his head wedged between iron fence posts. Hudson County Prosecutor's Office spokesman Gene Rubino has said prosecutors believe the teens were playing the game.

And earlier in May, Elex Murphy, now 20, was sentenced to life in prison plus 25 years in St. Louis for killing a Vietnamese immigrant as part the game in 2011.

Juvenile delinquency experts say a good punishment for these teens would be empathy training, such as volunteering at a homeless shelter. But a New York lawmaker proposed a bill this week that would make stricter sentences not only for those who do the punching, but for those who publish images online and watch the attacks.

"These twisted and cowardly thugs are preying on innocent bystanders and they don't care if the victims are young, old, a man or woman," GOP state Assemblyman Jim Tedisco said. "Life isn't a video game. These are real people whose lives are not only being put in jeopardy but in many cases destroyed."

Syracuse.com | The Post-Standard reporter Marnie Eisenstadt and Associated Press writers Mike Gormley in Albany, N.Y., Eric Tucker in Washington, D.C., Maryclaire Dale in Philadelphia and Kevin Begos in Pittsburgh contributed to this report.