At first, media reports and viral videos on social media said 50 people suffered cardiac arrest. The number of casualties now stands at 146.

The situation deteriorated fast as number of people dead in the incident went from initially reported nine to 59 and then 120 within an hour. A BBC report put the toll at 146 later. 

The injured had many women in their 20s, local media reports said. 

A huge crowd gathered at a central district of the South Korean capital for Halloween celebrations late on Saturday, the Yonhap news agency reported.

Around 100,000 people had gathered Saturday night in Itaewon, a central district of Seoul, lined with hundreds of shops and some very narrow streets, local news outlets said.

According to media reports, people gathered in such large numbers to participate in the event in the run-up to Halloween on October 31 after two years of muted celebration owing to Covid restrictions.

At around 11: 30 pm, scores of people fell unconscious near a hotel, reported The Korea Herald.

Fire authorities administered CPR to at least 50 people, according to the Yonhap news agency.  The Korea Herald report said that the fire authorities received 81 reports of people suffering from breathlessness.

Common people also attempted resuscitation, showed videos of the chaotic scenes from the spot. 

News agency AFP reported citing a fire department official that 140 ambulances had been dispatched to the scene.

Hyunsu Yim, a journalist with The Korea Herald, tweeted: "Absolute scenes of chaos in Itaewon right now as the Halloween night has turned into a major safety hazard with at least several party-goers being carried into ambulances."

He also attached photos of the incident.

He added: "I'm seeing pictures that I don't think is wise to share here but they are heartbreaking. I'm sure more details will come out later but what's certain now is tonight is going to go down as one of the most terrible and sad nights for Halloween in this country."

Before the stampede, several Twitter users posted warning to partygoers not to visit the place as it was overcrowded beyond control.

“Don't come to Itaewon. It's almost death-like here… My arm almost broke,” posted a woman along with videos.