When a blood-spattered man went on a stabbing spree in Sydney on Tuesday, killing one person and wounding another, witnesses chased him through the streets, uniting in a desperate effort to prevent him from hurting anyone else.
Dramatic footage from the scene showed civilians wielding chairs, an ax and even a milk crate as their defense, then successfully pinning the perpetrator to the ground as they waited for police to arrive.
Authorities called the quick-moving witnesses "heroes" and described them as "significantly brave people." On social media, they were celebrated as model citizens.
Those who helped put a stop to the attack in Sydney now join the ranks of a number of ordinary people from around the world who have demonstrated extraordinary courage to thwart mass attacks in recent years.
From Australia and Britain to France and New Zealand, witnesses have time and time again faced excruciating choices in the face of imminent danger, risking - and at times losing - their lives to try to save others.
Here are some of their stories.
On June 3, 2017, three terrorists wearing fake explosive vests drove into pedestrians on London Bridge before going on a stabbing rampage through the capital's bustling Borough Market. The attackers, who were later fatally shot by British police, killed eight people.
As the attack unraveled, Spanish banker Ignacio Echeverría challenged the attackers, clutching only his skateboard as a weapon. The 39-year-old was killed while attempting to save a woman being targeted by the attackers.
"It was like he didn't even think about it, but reacted immediately," Echeverria's friend said in a statement. Last year, Echeverría's parents accepted Britain's George Medal for bravery on their son's behalf.
Elsewhere in the market, others attempted to distract and challenge the attackers by hurling pint glasses, bottles and abuse at them as they waited for police to arrive.
One British soccer fan, Roy Larner, 47, who was out drinking pints with friends at the time of the attack, decided to tackle the trio, shouting slurs in support of his favorite team as he did so. Larner was stabbed eight times in the neck, head and hands, but lived to tell the tale.
He has since had a beer named after him.
During a knife attack at an underground station in east London in 2015, police tasered the perpetrator who reportedly yelled "This is for Syria!" as injured three people.
But what garnered the most attention was the voice of an onlooker captured in footage of the incident, shouting repeatedly "You ain't no Muslim, bruv!" at the suspect. ("Bruv" is the British slang equivalent of the American "bro.")
The comments went viral and trended as a hashtag on social media, as Brits praised the bystander for distancing the attacker's actions from Islam. Then-British Prime Minister David Cameron called it a "brilliant statement" in a news conference about the incident.
"Some of us have dedicated speeches and media appearances and sound bites and everything to this subject," he said. "But 'you ain't no Muslim bruv' said it all much better than I ever could."
When a white supremacist gunman went on a shooting rampage in two New Zealand mosques in March, he killed more than 50 people and wounded dozens of others.
At least one of his victims died trying to stop him.
Video footage released after the attacks showed Naeem Rashid, 50, trying to tackle the gunman, 28-year-old Brenton Tarrant, outside one of the mosques. The father of three, who had emigrated to New Zealand from Pakistan a decade earlier, was hailed as a hero in his home country after his death. Prime Minister Imran Khan awarded him a posthumous bravery award, and tweeted that he was "martyred" while trying to stop the gunman. Pakistan also declared a national day of mourning after the attack.
"My brother was a brave man who died to save others," Khurshid Alam, Rashid's brother, told The Washington Post in a telephone interview at the time. "His death showed how he cared for humanity."
On Saturday, Mohammad Rafiq, an unarmed 65-year-old, stopped a gunman from attacking a Norwegian mosque by throwing him to the floor. The retired Pakistani military officer said that the heavily armed suspect fought back, punching him in the face and shoving his finger into his eye.
Rafiq's effort to thwart what could possibly have been another deadly mosque shooting was supported by two other men inside the al-Noor Islamic Center who rushed to help pin down the aggressor.
Norwegian police said the men showed "great courage" and confirmed that they were treating the attack as a suspected act of terrorism.
Three young Americans were among around 500 passengers on board a high-speed train traveling between Paris and Amsterdam in 2015 when they heard a gunshot in the aisle.
A French citizen who chose not to be named publicly tackled the gunman, who was later identified as Ayoub El Khazzani, a Moroccan known to authorities. Then, Spencer Stone, Alek Skarlatos and Anthony Sadler jumped up to help hold him down.
Stone was serving in the U.S. Air Force and Skarlatos, who served as a specialist in Oregon's National Guard, had just returned from Afghanistan, where he was deployed. The three friends and a British citizen, Chris Norman, 62, were awarded the country's highest award, the Legion of Honor, in an official ceremony a few days later. The unnamed French citizen and French American passenger Mark Moogalian received the same award for their efforts at a separate ceremony.
Speaking at the ceremony, Hollande said Khazzani was carrying 300 rounds of ammunition. Witnesses who intervened to stop him helped France avoid "a tragedy, a massacre," he said.
"I did what I had to do," Norman told reporters after the ceremony where he was honored. "It wasn't heroism, it was what needed to be done in a situation of survival."
Earlier this year, the three Americans were also awarded French citizenship for their efforts.
A 13-year-old boy who saved 50 students from a school bus when it was hijacked and set on fire this year was granted Italian citizenship as a reward for his quick thinking and courageous efforts.
When the driver confiscated the phones of those on board the vehicle, Ramy Shehata hid his out of sight and pretended he was praying. He was actually making a desperate call to his father to ask for help.
The suspect was later identified as Ousseynou Sy, an Italian citizen of Senegalese origin. According to the BBC, he allegedly told the children on board the bus, "No one will survive," and pointed to African migrants dying at sea as his inspiration for the attack. Deputy Prime Minister Matteo Salvini has taken a hard-line stance against migration to Italy, but said some exceptions can be made for "acts of skill or courage," Italian media reported.