It might seem like a prank, but the knock-out game is real and extremely dangerous and being played in many parts of the country like New York, Chicago and D.C.

Some unsuspecting victims have even died.

The object of the game is to attack an unsuspecting person with a single punch, to see if you can put them on the ground.

A 78-year-old woman is among the victims.

"She's terrified. She will now not leave her building," said Chief Dean Esserman of the New Haven Connecticut Police Department.

In St. Louis and New Jersey, men died. These aren't muggings and these criminals don't want money; to them the game is a sport.

"Where young kids get together and attack you and rather than rob you they hit you and nothing more," said Esserman.

HPD hasn't seen the trend in the Houston area.

"It's the most ridiculous thing. I mean how could (you) do something like that," said Esserman.