As South Korea mourns the deaths of more than 150 people in a Halloween party crush, many people—even those not directly involved—are dealing with trauma and a search for answers that has at times blamed the victims, a psychiatry expert says.

Thanks in part to a flood of disturbing images in the first hours of the disaster, the emotional and mental health effects of the disaster touched all corners of society, said Ulsan University Hospital professor of psychiatry Jun Jin-yong.

"It spread very quickly through news media and social media, leaving people directly and indirectly affected, and even those who aren't affected may feel distressed and frustrated, pretty much casting a sense of dread over the entire society," he said.

The initial shock from the crush in the popular Itaewon district on Saturday night has turned to public outrage over the government's planning missteps and inadequate police response. 

Tens of thousands of revelers, many of them young, had crowded into the narrow streets and alleyways of Itaewon for the first unrestricted Halloween festivities in three years. An uncontrolled surge of people into one narrow alleyway turned into a deadly crush. 

Disturbing footage showing emergency rescue officials and citizens providing cardiopulmonary resuscitation (CPR) to unconscious victims quickly went viral on social media even before the nature and the scale of the disaster became known. 

The graphic images were replayed on mainstream news media. Then speculation about what caused the disaster began to swirl.

"What makes it harder for most people is that it was nobody's fault that they happened to be there and when you keep asking why they were there in the first place [...] that's a recipe for social conflict," Jun said. 

The death toll stands at 156, with 172 injured, 33 of whom were in serious condition. 

The government sent a mobile clinic run by the National Center for Disaster Trauma to Itaewon, offering free counseling.

Jun said there was a natural human tendency to look for an explanation for a disaster, placing blame on people or a set of circumstances, Jun said. 

"When you see reactions to disasters, there are inevitable reactions trying to find some scapegoats and blaming them," Jun said. "For example, when we had COVID-19 cases the first time in South Korea, there were a lot of blaming reactions like 'Why did you go there? Why did you spread it to others?’ "

Kim Bum-jin, 18, said recurring memories of the disaster have made him unable to sleep or eat. "The memories keep coming back, so now I get a panic attack when I hear any siren sounds."

"Everyone was there to enjoy a festival. No one knew that an accident would happen," Kim said. "I don't understand how people can blame [the victims and survivors]."

Hwang Jung-soon, 75, mourned at a memorial altar set up in front of Seoul's city hall. She said the scope of the disaster was hard to comprehend.

"I've been watching the news over and over and feeling so sad. I feel depressed, can't eat and have a headache," she said. "This news just doesn't make any sense."