Here’s how the Seoul Halloween crush happened

But over the past two decades, Itaewon was cleaned up. By the time the American military left the South Korean capital in 2019, it already had a reputation as an open and diverse neighborhood, known for its bright bars, restaurants, cafes and shops.

That reputation made it a natural place to celebrate Halloween, an imported holiday increasingly popular with young South Koreans. An estimated 100,000 people were in the neighborhood on Saturday, the first pandemic-era Halloween since social distancing restrictions were lifted.

This year, Itaewon’s Halloween turned to horror. As huge crowds pushed into the neighborhood to celebrate, there was a crush. More than 150 people were killed and about 82 injured, according to fire department officials.

Live updates: The latest news on the Seoul crowd crush

Investigations into what caused the tragedy are still ongoing. But videos from the scene suggest that the tight streets and alleyways that lent the neighborhood its charm hadn’t been able to cope with the scale of the revelers that descended upon it.

Videos show that even hours before the crush began, large numbers of people were congregating in the area. On social media, some said they had arrived in the area by late afternoon because they expected a huge crowd — but even then they were shocked by the size of the crowds.

The situation near the Hamilton Hotel, a four-star property, was particularly dire as crowds tried to squeeze through a narrow alleyway nearby.

A live stream that began at 7:41 p.m. shows the top of the alleyway. The intersection is crowded, but people are able to walk through the street, albeit slowly.

“Despite some narrow passages, the situation appears to be altogether not, or not yet, critical,” said Dirk Helbing, a professor at ETH Zurich who has studied similar events, including the 2010 Love Parade disaster. Helbing however noted that pedestrians can be seen temporarily halted at times in the footage.

Another live stream broadcast at 9:21 p.m. — about an hour before the first calls to authorities — shows what Keith Still, a crowd safety expert and visiting professor of crowd science at the University of Suffolk in England, called “high density” crowds that are still able to move at the intersection. But there are signs of trouble.

“You can see the static crowd ahead and people moving towards that area, that’s indicative of a potential problem,” said Still

And despite the building danger, “there is no crowd management in place whatsoever,” said Steve Allen, founder of Crowd Safety, who reviewed the videos. “Was a crush inevitable as numbers grew? Definitely.”

Video taken at 10:08 p.m. shows large numbers of people near a second intersection on the road where it meets an alley that leads down to the metro station on the east side of the hotel. The video shows what “appears to be a crowd collapse ahead,” said Still. “But the crowd will not know that and may continue to move forward.”

At the first intersection, a video shows that the situation has grown critical. There is evidence of “crowd turbulence,” Helbing said, as individuals are carried by waves of movement that ripple through the crowd. It’s an environment where small movements are capable of causing “progressive crowd collapse” Still said.

According to South Korean authorities, the first call for help came at 10:15 p.m., hours before the usual peak party time in Seoul, with emergency responders arriving just a few minutes later.

Images from later in the evening showed the aftermath of the crush — including people performing chest compressions on young men and women who were not moving.

In some photos, victims are fully covered with blankets on sidewalks and streets.

Even as the tragedy unfolded in the neighborhood, some nearby bars were packed until at least 5 a.m. — the crowds apparently unaware of the tragedy that had taken place just a short walk away.