Remember a few years back when all everyone could talk about was the so-called “Knockout Game?” It was a short-lived craze that was a mixture of real danger and a little bit of media hype.

Now, some say a mob attack by dozens of children and teenagers near Temple University on Friday could be the resurrection of the Knockout Game. While police haven’t confirmed what the motive was for the brutal assaults, a Temple student told CBS News in Philly that police in the area were talking about how the children were playing the “Knockout Game.”

Here’s a rundown of what happened and why it might be related to the old trend:

The attack near Temple

Up to 100 children and teenagers swarmed an area near Temple University on Friday evening in an incident that ended with four juveniles arrested and one person hospitalized, according to NBC 10.

Police said for nearly two hours, the mob of young people wreaked havoc in the area of the university, punching students, throwing rocks at cars and tossing a cop to the ground. Six Temple students were hurt in the attack, as was a university police officer and a Philadelphia police horse that was punched by one of the teenagers.

One of the victims told The Tab that she was walking near 16th and Oxford streets when she and her boyfriend were approached by a group of what she estimated to be 40 kids.

“We then crossed the street but two kids followed us and hit my boyfriend,” she said. “My boyfriend ran and got away but the second I tried to run, they grabbed me by my hair and started beating my head and back.”

Since the mob-style attack, Temple Police and Philadelphia Police have said they’re stepping up their presence in the area, but neither have offered a motive for why they think the teenagers targeted random Temple students and officers.

What the ‘Knockout Game’ is

The idea of the Knockout Game was that children and teenagers would compete against each other to see who could knock out an unsuspecting victim, so they’d approach random folks on the street and punch them as hard as they could.

Experts said it was a way for children to act out on thrill-seeking tendencies. They also pointed out that, at the time, victims who were targeted were someone young people considered to be “an other” — a person who is a different race, religion, class or age than the child.

“We know from brain studies that the part of your brain that gets fired up through excitement and thrill-seeking actually develops more quickly and fires up more quickly than the other part of your brain, which comes along a few years later and is about judgment and discretion,” Jeffrey Butts, a youth criminal justice expert at John Jay College, told CBS.

There have been similar trends to the Knockout Game, some of which are rooted in the Internet. In 2013, right around the height of the Knockout Game’s popularity, teenagers were using Vine to spread the “#SmackCam,” a game that basically involved teenagers walking up to random people and slapping them in the face.

The was also the “flash mob” issue. In 2011, former Mayor Michael Nutter instituted a curfew in order to curb problems associated with roving, violent groups of young men who organized on social media.

The Knockout Game in Philly

This has not been a widespread problem in Philly, but there have been a handful of documented incidents in the Philadelphia area that police suspected were perpetrated because the individuals involved may have been playing the Knockout Game.

Here’s a breakdown of the incidents we tracked down:

October and November 2013 – Lower Merion

Two incidents of kids playing the Knockout Game in Lower Merion were reported. In one case, an elderly man was hit in the face by a kid who apparently did it “on a dare.” In another case, a 63-year-old man was ambushed while walking his dog.

November 2013 – Center City

Philadelphia Police suspected a man who was caught on video punching random people in the face may have been playing the Knockout Game. The man, on two separate occasions, punched a woman in the face near the Broad Street Line and ran away without taking anything.

November 2013 – Northeast Philly

Police in Philadelphia arrested a 15-year-old whom they said took part in a “knockout”-style attack on Nov. 11, 2013 at a pizza shop in Fox Chase. The victim told CBS Local at the time that he was walking out of the Northeast Philly pizza shop when he was approached by several kids who beat him and didn’t take anything. “There’s no reason at all. I mean, I didn’t get robbed, they didn’t take nothing from me. They just beat me up,” the man told the TV station.

June 2014 – Upper Darby

Police arrested an 18-year-old who they said was one of four suspects in an attack on a homeless man at a trolley station in Upper Darby. In broad daylight, the suspects attacked a 58-year-old homeless man

April 2015 – Center City

A 16-year-old turned himself into police and was charged with aggravated assault after police said he knocked out a 60-year-old person riding SEPTA on the 15th Street Market-Frankford line. Police didn’t confirm the teenager was definitely playing the Knockout Game when the incident occurred, but it was suspected.