Before Saturday night, the narrow streets of Itaewon, a popular nightlife district in Seoul, South Korea, were known for attracting party-goers and tourists.

Now Itaewon’s tight alleyways are associated with a tragic, mass casualty crowd crush event where more than 150 people died and more than 100 were injured while trying to enjoy Halloween celebrations.

Itaewon is a popular commercial destination for Halloween and is lined with bars, clubs and restaurants that had opened their doors for the first mask-less celebration in two years.

Thousands entered the district, and by 10 p.m. the narrow alleys were packed.

Multiple videos posted on social media platforms from the scene during the crowd crush show people tightly pressed against each other, with no room to move.

Witnesses have told The Associated Press that the crowding quickly turned chaotic and deadly as people were trapped for as long as 40 minutes. In some places, people toppled over one another in and ended up stacked like dominos. 

Emergency aid workers were overwhelmed by the number of bodies retrieved and were calling out to the crowd to help administer CPR, witness Ken Fallas told the AP.

Officials in South Korea have admitted fault and issued an apology on Tuesday. An initial police investigation found that police did not respond to phone calls for help effectively, the AP reported Tuesday.

Experts who have studied public safety and the issue of crowd crushes for decades say a multitude of factors contribute to events going horribly wrong like in Itaewon, and there’s a great deal that could have been done in advance to prevent such a disaster.

CTVNews.ca spoke to several academics whose research focuses on crowd crushes and surges about what went wrong in Itaewon, how crowds can be managed safely and how to protect yourself.

WHAT IS A CROWD CRUSH AND WHAT HAPPENED IN ITAEWON? 

A crowd crush can happen when there is immense overcrowding and the density builds up to the point where it’s almost impossible to get out, said G Keith Still, a visiting professor of crowd science at the University of Suffolk in England.

“A fall in high density can have these catastrophic consequences,” said Still. Injuries in incidents of overcrowding are not entirely unusual, they can sometimes turn more extreme, like in Itaewon, he said.

“Unfortunately for some people, the first time they experience [a crowd crush], it’s too late for them to do anything about it. It’s not to do with the numbers of people, it’s due to the exposure of high density,” he explained.

Still said that if he was asked to do a risk assessment of Itaewon, he would have immediately said “there’s a finite number of people who can fit into this space.”

The issue with Itaewon’s popularity in this case is that the district is made up of narrow streets and alleyways that connect, providing little space for what became a huge number of people, said Ali Asgary, a professor at York University and an expert in disaster, emergency and business continuity management.

“There was no management of the event there or crowd management system. It all led to this unfortunate event,” he said. 

WHAT SHOULD HAVE BEEN DONE IN ADVANCE?

A risk assessment would involve looking at the space, seeing the routes people can take, and understanding who is attending the event and their motivations, and then implementing countermeasures to prevent a crowd crush, said Still.

“The way I liken that is to a tachometer on a car. There’s a red line. If you rev the engine above the red line, it’s going to blow up. It’s the same as crowd density– you need to keep the crowd below that density in order to keep it moving,” he said.

Gil Fried, a professor at the University of West Florida in the administration and law department, said the first thing that jumped out to him about Itaewon was how the area looks, and how the alleys are surrounded by walls.

“Barricades or anything that constrict people and pin them in, that’s going to be a concern,” he said.

Another issue, outlined during a cabinet council meeting Tuesday by President Yoon Suk Yeol, is that South Korea lacks resources on crowd management. Police told reporters that only 137 officers were in that area that night when as many as 100,000 people arrived to celebrate Halloween.

While that was more officers than in 2017 to 2019, where only 34 to 90 officers were allocated to the area, police acknowledged that the officers were assigned to mostly deal with crime and narcotics use, not crowd control. 

Beyond the number of police assigned to the area, specially trained experts should have been involved as well, experts say.

According to the National Fire Protection Association in the U.S., an event requires one trained crowd manager per 250 people, said Fried.

“Police officers aren’t necessarily trained to deal with a crowd,” he said. Police may know what to do when a crowd gets out of hand, but not what to do proactively to minimize the potential for concerns around crowd crushes, he said,.

At least 400 trained crowd personnel should have been in Itaewon, said Fried.

Other factors that impact strategy are the weather, whether water is in the area, and if the crowd might be drinking or under the influence of drugs, he explained.

“When you have people being funelled into these narrow alleyways, that’s a recipe for disaster, because you want as much space as possible,” he said.

The space needs to be monitored, and personnel have to stop more people from entering until the situation is addressed, said Still.

“This is done at Christmas markets all the time….it’s very simple to regulate, if and only if you understand the risk. That’s the problem here, they didn’t see the problem before it happened,” he said.

Crowd movements can be controlled to ensure there's enough space so that emergency services can reach people at any point, said Asgary.

“It could have helped a lot, although, if I was there and even thinking about having such a large number of people in that area, I wouldn’t even advise that,” he said. “But if people want to use that space…the numbers should be reduced,” he said.

HOW CAN A CROWD CRUSH CAUSE DEATH? 

The majority of deaths caused by a crowd crush are due to a lack of oxygen, not injury, said Asgary.

“This is not something because your leg is broken, it’s because of the pressure that causes harm to your internal organs that are not able to function with blood circulation or oxygen circulation,” he said.

Experiencing horizontal and vertical pressures, where people are pushing from the sides and the front and back, along with on top of each other, makes it difficult to breathe, he explained.

“It may not show signs of injury from the outside, but it’s the pressures from internal organs that cause this situation,” he said. “But if you are crushed against a wall, you will face injuries from the outside as well,” he said.

Crushing injuries, where multiple people end up on top of each other, create a significant amount of force that can harm a body, said Fried.

He said he’s worked on cases where metal rails have been twisted due to a crowd crush— indicating a significant amount of force had pushed a person against the railing. That would take more than 1,000 pounds per square inch, he said.

“It’s like drowning. There’s nothing you can do, if there’s three or four people on top of you, there’s this sense of hopelessness,” he said.

HOW CAN YOU SURVIVE A CROWD CRUSH? 

While there can be a certain point where it is impossible to escape a crowd crush, Fried recommends “situational awareness,” which is being aware of surroundings at all times.

“Understand what’s going on and try to take steps that will minimize the likelihood…knowing where your exits are, if there’s general admission, don’t go to the front,” he said.

“One of the things we always tell people is always carry water. You could be stuck there, and there are numerous cases of dehydration,” said Fried.

He recommended that someone stuck in a crowd see if they can stabilize themselves and move with the movement of the crowd, because in these situations, what happens is individuals become like “fluid,” said Asgary.

“We will not be able to control ourselves anymore, we follow with others and move with them. If we start to push or press, it’s not going to help. We just need to relax and calm down.”

He said those involved should do their best to save their oxygen and protect body parts that are important for breathing, and focus on breathing, rather than pushing.

WHAT ARE SOME MISCONCEPTIONS ABOUT CROWD CRUSHES?

With crowd crushes, sometimes blame is placed on the crowd rather than on the organizers and government services that were supposed to provide a safe environment, said Still.

“It’s not up to the members of the public to consider the safety plan,” he said. “When you go to a nightclub or a night time economy, it’s a duty of care for the people that are managing to provide a safe environment,” said Still.

There are no “stampedes” in cases like these, no one is running, said Still.

“Nobody in that crowd went with the intent of reacting in this way,” he said. “It wasn't them going to create a problem or harm, it’s reacting to the situation they found themselves in.”