On July 15, a man entered the Beicai branch of the Agricultural Bank of China, took a teller hostage at knifepoint and demanded money.

According to a surveillance video that catches the robbery already in progress, the robber has forced the teller to the floor. He clutches her wrist in one hand and holds a meat cleaver in the other. He repeatedly threatens to bring the cleaver down on the teller, as bystanders look on, urging him to stop, according to a news report on ifeng.com, the Internet portal owned by Phoenix New Media.

The standoff doesn't last long. The robber makes a few more chopping motions toward the teller, and then takes off for the door. The teller scrambles away.

The robber doesn't make it very far. The bank's doors are locked. He ends up beset by two security guards, one who holds a chair lion-tamer style, along with an ageing female janitor wielding a mop handle. The three, along with two bystanders, pursue the robber around the bank's lobby. In the video, one bystander tosses a chair at the robber. They eventually subdue him without suffering injuries. 

The bank gave each of the five crime fighters 10,000 yuan ($1,600), plus a commendation certificate. The public security bureau also gave each of them 10,000 yuan and nominated them for the city's "model of Shanghai individual Samaritan" award. The janitor, surnamed Gu, who is in her 60s, was particularly lauded online for her skill with a mop handle.

The praise is deserved. I also applaud their courage. However, I don't think similar actions should be encouraged among the rest of the public, especially under circumstances where there is so little to gain and a lot to lose.

Although the story has been framed as a heroic hostage rescue, the video footage clearly shows that the robber had released the teller well before the others confronted him. They didn't put themselves in harm's way to save a life, but to ensure a bank robber didn't escape.

One might argue that they had to confront the robber because they were all locked in the bank together and couldn't afford to let him take another hostage. I'm sympathetic to that argument. But it strikes me that it would have been simpler and safer to unlock the doors and let the robber flee. His face was clearly visible in the bank's surveillance video, and police have shown they are capable of using video footage to track down criminals.

In some ways, the circumstances heavily favored the citizens. They had the robber outnumbered five-to-one and didn't have to worry about anyone else getting hurt. But superior numbers don't ensure zero casualties. The bank employees and bystanders weren't as well-armed as the robber, who could have seriously wounded one of them with his cleaver.

They were brave, but they also got lucky.

There might be times when it is necessary for bystanders to stand up to violent criminals, such as when someone's life is actually on the line, but this wasn't one of those times.

To be clear, I'm not saying that the people at the Agricultural Bank of China shouldn't have stood up to the robber, only that future bystanders should carefully consider whether taking on an armed bank robber is worth it.

The two security guards, the two bystanders and the elderly janitor deserve our praise, but perhaps more for defying the stereotype that Shanghai residents don't care to stick their necks out for someone in trouble.

These citizens might have been heroes, but they didn't have to be.