Social media in Shanghai was alight this past Friday following a public knife attack near People's Square. In a real-time unfolding of events, Weibo and WeChat feeds from hundreds of eyewitnesses provided minute-by-minute accounts of the attack, including photos, videos and commentaries.

According to the live coverage, at about 12:30 pm a barefooted man began stabbing random people near Nanjing Road Pedestrian Street. After being incapacitated by a "Good Samaritan" foreigner, the suspect fled along Xizang Road until he was pursued and apprehended by a lone off-duty traffic assistant. The entire incident occurred within a time-span of 10 minutes. The swiftness of the knife-wielding madman was matched only by the swiftness of smartphone-wielding passersby, their photos and reactions instantaneously uploaded online to be devoured by millions of netizens such as myself.

As a media professional, I am fascinated by the new phenomena of social media, which has organically become an integral part of modern mass communication. The public's technological ability to share everything long before surveillance systems can be reviewed by authorities has proven to be a powerful utility in not only alerting the world to breaking events, but in the subsequent analysis of these events.

The problem, however, is when social media veers away from merely responding to news and begins to define the news. The propensity of these so-called "citizen journalists" to spread misinformation has turned our social media platforms into cesspits of rumor and calumny. It's not always intentional or malicious, but the inability of the average layperson to accurately analyze events often does more harm than good.

I was at home making dumplings when my WeChat Moments was suddenly flooded by a stream of play-by-play accounts of the knife attack. Comments like "killing spree on Nanjing Road!" had me fearing the worst, even though in actuality only three people were injured, and only superficially. Not until the story was reported by traditional news outlets, along with statements from the authorities, was I made aware of the truth.

Now imagine the ensuing public panic when millions - nay, billions - of other ordinary citizens not unlike myself are fed a real-time stream of misinformation.

But what really leaves me questioning the public's newfound obsession with documenting incidents like this knife attack is their unwillingness to actually get involved in the situations in front of them. Hundreds of Weibo accounts showed virtually the same pedestrian videos of the traffic assistant, surnamed Fang, taking down the attacker, surnamed Zhang.

But what only closed-circuit surveillance system footage could show is the bigger picture: a lone man fighting the perpetrator while dozens of people stand around them filming with their mobile phones. Not a single one of them intervenes; they are all more concerned with recording Fang being cut up by a lunatic than with helping him stop the lunatic.

And to what end? So that they can brag to their social networks that they were there? So that they can get more "likes" and followers on WeChat and Weibo? What if Fang had had the same apathetic attitude as those hundreds of eyewitnesses and just stood there stupidly holding up his mobile phone to capture the action while Zhang slashed his way through the crowds? How many more people would have been injured, maybe even killed?

Technology has empowered us as civilians, but it has also made us more callous. We see so much with our smartphones that we no longer see with our own eyes. We allow people to get hurt or even die while we stand idly about, utterly unwilling to get involved because it's become more important to us as a society to document a tragedy than to try to prevent it.

Traffic assistant Fang is just an ordinary warden whose only responsibilities are crowd control at Shanghai's most popular shopping street. Fang had just finished his shift and was heading home when he witnessed the attack. He suffered cuts to his face and leg while disarming Zhang. His brave actions should serve as a reminder to the public that senseless tragedies can be prevented if more people put down their phones and get involved. Instead of recording the heroes, let's be heroes.