In a night of fun for tens of thousands of Halloween revelers, a bottleneck in a narrow alley of Seoul’s entertainment district instead claimed 156 lives, with analysts and top officials blaming a crowd control failure.

A lack of prior safety planning — officials concede it was insufficient — quickly turned South Korea’s first Halloween without coronavirus restrictions into one of the country’s worst disasters, with police relying on bystanders to pull partygoers out of the crowd.

“In most cases of crowd crushes, it turns out that the root cause is a lack of planning,” said Eric Kant, who runs Netherlands-based Phase01 crowd management.

Since there was not a single organizer, the government did not require any of the bars, clubs and restaurants holding events in Itaewon on Saturday to submit a safety management plan.

And although police predicted in advance that the boisterous celebrations would swell to an estimated 100,000 people, they deployed just 137 officers – compared to the 6,500 sent across the city to patrol a protest that covered just a fraction of the size matters.

As public scrutiny over mass policing mounted, Seoul’s police chief, interior minister and mayor on Tuesday apologized for failing to prevent the deadly disaster.

South Korea’s prime minister said Wednesday that police must explain their slow response to multiple emergency calls made in the hours leading up to the disaster.

However, some experts suggested that more policing alone might not have been enough to avert the tragedy.

“Either they become part of the crowd themselves and their lives are in danger, or they become mere observers who don’t even have enough information about what’s happening in the crowd,” Milad Haghani, a crowd safety expert at the University of New South Wales, told AFP.

According to Haghani, Itaewon’s Halloween celebrations ticked all the risk factor boxes for crowds.

The typically boisterous neighborhood is crisscrossed with narrow streets that lack an obvious “potential escape route.”

Then there were issues related to the lack of organization of the event itself, including “unrestricted entry” of people into a small space, “no ticket sales” that left no accurate estimate of demand, and no active crowd monitoring.

“This is a recipe for disaster at mass gatherings,” Haghani said, adding that it “reminiscent” of Germany’s 2010 Love Parade, but with “far more casualties.”

During this free music festival, 21 people died from asphyxiation and hundreds more were injured when crowds tried to escape a ramp leading to the event.

Such incidents are often caused by “mismanagement by event or venue organizers” rather than “panic” in the crowd, said John Drury, an expert in crowd psychology at the University of Sussex.

In Itaewon, witnesses on Saturday told AFP that partygoers sustained injuries at a certain bottleneck early in the night simply because of the crowd.

Less than two hours later, people spontaneously began falling over and then stomping on each other in a tight knot of bodies, making it all but impossible to move or breathe.

To avoid too many bodies being crushed in too small a space, such street events require “monthly planning” by experts, said Kant in the Netherlands.

This includes the prior calculation of visitor capacity and then counting and monitoring the crowd and possible bottlenecks either on the ground or via video surveillance.

“If maximum capacity is reached during the event, further access to that area should be effectively blocked,” Kant added.

It wasn’t until around 2:00 am, or more than seven hours after the first 911 call, that officials barred everyone except officials and medical personnel from Itaewon.

National police chief Yoon Hee-keun acknowledged that officials had not adequately responded to the many calls from citizens warning of dangers while the interior minister promised an investigation into exactly what happened in Seoul.

“I am 100 percent convinced that this tragedy was avoidable,” Kant said.

“Crowd crushes or crowd disasters were and are always foreseeable, i.e. avoidable.”