Wiping away tears, Song Jung-hee laid a single white chrysanthemum at a memorial for the 154 victims of a fatal crowd crush in South Korea.
What was supposed to be a Saturday night of post-pandemic celebration in Seoul's popular Itaewon nightlife district turned into one of South Korea's deadliest disaster.
With tens of thousands of people crammed into a narrow alleyway -- and police and crowd control measures nowhere in sight -- eye-witnesses have described how partygoers became trapped, crushed and suffocated in a human surge.
"I wish we could have protected them," 69-year-old Song told AFP, as she wiped her eyes with a handkerchief.
"I feel guilty -- we have let the young people down."
Around Song at the altar set up in central Seoul were mourners in various states of distress. Many sobbed as they placed a flower down, with some in office suits -- coming to pay their respects during their lunch break -- queuing for their turn.
"I cried all night for the poor young people we lost. They were so young, in the prime of their life," said 71-year-old Park Sun-ja, whose eyes were raw and swollen behind sunglasses.
"It is such a loss for our country," she told AFP.
The youngest of the victims were schoolchildren, South Korea's education ministry confirmed Monday, but most were young women in their 20s.
"The victims were young. I'm a similar age and I'm just devastated by what happened," 19-year-old student Hwang Gyu-hyeon told AFP.
"I can't believe this accident happened despite the signs that were clear beforehand," she said. "Nothing was done to prepare for this crowd."
There is growing criticism in media and online over failures in policing and crowd control at the Halloween event. The government has defended the level of police deployment.
But many mourners at the memorial altar laid the blame squarely on the authorities and the lack of crowd control measures.
"If only there had been more police officers to keep order, this would not have happened," Song said angrily.
The 154 victims included people from more than a dozen different countries, from Australia to Vietnam.
Japanese businesswoman Chi Naomi, 46, said the death of two of her compatriots had brought the disaster home for her.
"It doesn't feel like someone else's tragedy," she said, adding that in Japan, young people also enjoyed Halloween celebrations, but authorities made sure they were safe.
"I wonder why there wasn't proper control in Itaewon on that day," she said.
"I've been to the site myself, and it is such a small alley. They could have taken so many steps, like making the alley a one-way or limiting the number of people there. I don't understand why these steps weren't taken."
At a second official memorial in Noksapyeong, near Seoul's new government offices, a group of policemen came to pay tribute to the victims, many looking visibly moved as they laid white flowers on the altar.
Wearing yellow jackets, a group of families linked to South Korea's 2014 Sewol ferry disaster, in which 304 people -- mostly schoolchildren -- died, also came to the Noksapyeong memorial to pay their respects, weeping as they laid flowers at the altar.
At a makeshift memorial close to the narrow, three-meter-wide (10 feet) alleyway at the epicenter of the disaster, Buddhist monks chanted prayers for the dead.
Friends hugged and comforted each other while they added their flowers and other tributes to the growing pile at the scene, which soon took up much of the sidewalk.
British tourist Robyn Lindsay told AFP that she and her friends were at the Itaewon Halloween event on Saturday night.
"But we left before it got too crazy because it was just too much," she said, adding that they managed to get out and head home before the disaster.
"We were very, very lucky," Lindsay said, wiping away tears as she paid her respects at the street-side shrine. "We are just thinking about all the victims and their families."