American tourists and friends Alek Skarlatos, Spencer Stone and Anthony Sadler didn’t wake up one morning last week with thoughts of becoming heroes.

Heroism stems from circumstances, when average people arise to perform uncommon actions in the midst of adversity. These Americans’ circumstances? They were aboard a high-speed train Friday from Amsterdam to Paris, along with Ayoub El-Khazzani, a 26-year-old Moroccan wielding an AK-47, a pistol and a blade.

The men had decisions of a lifetime to make. Do they face death cowering in fear, or do they fight back and risk being killed in the aisles?

In an instant, they, along with British businessman Chris Norman, rushed and tackled the gunman, ending an attack that could have turned into a massacre. And, over the weekend, they received the Legion d’Honneur from France’s president Francois Hollande at the Elysee Palace, congratulations from President Barack Obama and the smiling approval from millions worldwide.

Could we have been as brave or as selfless as these men, or those passengers aboard United Airlines Flight 93, who sacrificed their lives to thwart a bigger 9/11 terrorist plot? It is difficult to say, but this much is certain: Vigilance matters, and seconds count.

Sadly, such life-threatening moments have occurred in movie theaters, malls schools, hotels, office buildings, military bases and even outside police headquarters. No place where people congregate is 100 percent safe.

Still, every attack on innocent people is a rebuke of the canons of civil society. The train attack leaves us wondering whether security at train stations should have been tighter, whether global intelligence agencies missed signs of a possible terrorist attack. El-Khazzani, who had had been identified as a radical Islamist, reportedly traveled recently to Syria to acquire weapons, yet managed to board a heavily traveled train with enough weaponry and ammunition to kill hundreds. And he may have had it not been for the quick actions of a National Guardsman, an Air Force serviceman and a college student, all sharing a vacation in Europe.

Now the trio is globally celebrated, though Sadler says they were only responding to a crisis. “The gunman would have been successful if my friend Spencer had not gotten up,” he said. “I want that lesson to be learned. In times of terror like that … please do something. Don’t just stand by and watch.”

Society needs more true heroes, people like Skalatos, Sadler and Stone, who displayed deeply rooted character and selflessness. This time, the good guys won, and the world owes a debt to their courage.

Editorial by The Dallas Morning News