New York (CNN) — A sick so-called game known as “knockout” — where teens appear to randomly sucker-punch strangers with the goal of knocking them unconscious with a single blow — is catching the attention of law enforcement throughout the nation.

The assaults can be fatal. In New Jersey, Ralph Santiago, 46, a homeless man, was walking alone in Hoboken on the night of September 10 when he was suddenly struck from behind, said Hoboken Detective Anthony Caruso.

The blow knocked out Santiago, who had a pre-existing brain injury. He suffered a seizure. The victim’s body struck a nearby fence, with part of the wrought iron fence piercing his body and killing him, Caruso said.

Surveillance video in the area showed three teens running from the scene. Two weeks later, police arrested the juveniles and charged them in connection with the killing. Caruso said the attack was unprovoked.

Authorities have reported similar incidents in New York, Illinois, Missouri and Washington.

One of the latest attacks happened Friday, when someone was allegedly punched on a street in Brooklyn. Police brought four men in for questioning and arrested 28-year-old Amrit Marajh.

Marajh is charged with aggravated assault as a hate crime, assault as a hate crime and assault in the 3rd degree, police said. He was arraigned Saturday, according to Mia Goldberg, spokeswoman for the Kings County District Attorney’s Office.

Youth violence expert Chuck Williams blamed the media and parents for what he called extreme aggression by America’s youth. Negative attention, he said, is often rewarded.

“That’s America. America loves violence and so do our kids,” Williams said. “We market violence to our children and we wonder why they’re violent. It’s because we are.”

Williams, a professor of psychology and education at Drexel University in Philadelphia, said some young people are desperate for attention. He called it the “Miley Cyrus effect,” where teens will do anything to get noticed, no matter how heinous or unconscionable.

“These kids know the consequences,” he said. “They want to get arrested. They want to get caught, because they want that notoriety. They know they won’t go away forever because they’re kids. It’s a win-win all around for them.”

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In New York, police noted seven “knockout” incidents this fall alone. Some of the incidents were allegedly directed specifically at Jewish people and thus classified as hate crimes, said police spokesman Sgt. Brendan Ryan.

Despite the recent assaults, Ryan cautioned that police in New York haven’t yet seen evidence of a “knockout” trend.

“We know that NYPD, and especially the Hate Crime Task Force, are working swiftly to find the alleged perpetrators of these incidents,” said Evan Bernstein, the Anti-Defamation League’s New York regional director, referring to a spate of assaults in parts of Brooklyn.

Rabbi Yaacov Behrman, a resident of Brooklyn’s Crown Heights neighborhood and executive director of the Jewish Future Alliance, said many of the assault victims are children. Behrman met with black leaders last week to discuss the issue.

“Kids talk, especially on social media. There’s a buzz about this,” said Behrman.

New York Police Commissioner Raymond Kelly on Wednesday deployed additional police officers to Crown Heights, a Brooklyn neighborhood where eight “knockout” attacks have occurred, including an assault on a 78-year-old woman, police said.

In Pittsburgh, police spokeswoman Diane Richard said reports of the “knockout” game in the area first surfaced last year.

In October 2012, an English teacher was strolling through an alley in Pittsburgh to his parked car, Richard said. The teacher, James Addlespurger, 50, was approached by a group of teens, Richard said.

One of the teens punched Addlespurger in the face. The teacher fell and struck his head on the concrete ground. The assault, like so many others, was caught on video surveillance tape, and a 15-year-old was later arrested, Richard said. It is unclear whether the assault was part of a specific game.

Kelly, the New York police commissioner, said he is concerned about copycats in his city in the wake of recent news reports.

“When you highlight an incident or a type of criminal activity, some people will simply try to copy it,” the commissioner said Friday. “It’s a phenomenon we’ve seen before.”

Republican New York State Assemblyman Jim Tedisco on Wednesday proposed new legislation he’s calling the “Knockout Assault Deterrent Act,” calling for juveniles charged with the random assaults to be tried as adults.

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“Violence like this should not be condoned no matter the age of the offender,” Tedisco said in a statement. “Youth should not be an excuse for this kind of behavior.”

At the same time, Detective Brian Sessa said that it “is yet to be determined” whether the alleged assaults in New York were isolated or part of a larger phenomenon. And since Santiago’s death in Hoboken, police there said they have not seen any other such incidents in the area.

Richard warned that people who seem distracted — checking smartphones or listening to music while walking — can be more vulnerable to assaults.

In New York last week, Jewish and African-American community leaders met in an effort to smooth relations among young people. “Knockout” assaults were a big part of the discussion.

“To go around and harm just anybody on the premise that you want to show your bravado is not to be accepted in our community, in Crown Heights, in Brownsville or anywhere else for that matter,” community activist Tony Herbert told CNN affiliate WCBS. “Keep your hands to yourself. That is stupid.”

CNN’s Rande Iaboni, Rob Frehse, and Chris Kokenes contributed to this report.