At least 153 people were killed and 133 injured after a crowd surge on a narrow street during Halloween festivities in Seoul, South Korean officials said.
President Yoon Suk-yeol declared a period of national mourning and designated Seoul's popular Itaewon district a disaster zone after the Saturday night disaster.
The Ministry of the Interior and Safety said the death count could further rise as 37 of the injured people were in serious conditions.
Those killed or hurt were mostly teenagers and people in their 20s, Mr Choi said. The dead included 22 foreigners, he said, including an unspecified number of people from China, Norway, Uzbekistan and Iran.
During a televised speech, Mr Yoon said supporting the families of the victims, including their funeral preparations, and the treatment of the injured would be a top priority for his government.
He also called for officials to thoroughly investigate the cause of the accident and review the safety of other large cultural and entertainment events, including regional festivals, to ensure they proceed safely.
“This is really devastating. The tragedy and disaster that need not have happened took place in the heart of Seoul amid Halloween (celebrations),” Mr Yoon said during the speech. “I feel heavy hearted and cannot contain my sadness as a president responsible for the people’s lives and safety.”
UAE President Sheikh Mohamed sent condolences to Mr Yoon and wished the injured a speedy recovery.
After the speech, Mr Yoon visited the Itaewon alley where the disaster occurred.
An estimated 100,000 people had gathered in Itaewon for the country’s biggest outdoor Halloween festivities since the coronavirus pandemic began and strict rules on gatherings were enforced, AP reported.
The South Korean government eased restrictions in recent months and this was the first big chance for many young people to get out and party.
It was not clear what led the crowd to surge into the narrow downhill alley near the Hamilton Hotel.
One survivor said many people fell and toppled one another “like dominoes” after they were being pushed by others.
The survivor, surnamed Kim, said they were trapped for about an hour and a half before being rescued, as some people shouted for help and others were short of breath, according to the Seoul-based Hankyoreh newspaper.
Another survivor, named Lee Chang-kyu, said he saw about five to six men push others before one or two began falling, according to the newspaper.
While Halloween is not a traditional holiday in South Korea, it is still a major attraction for young adults, and costume parties at bars and clubs have become popular in recent years, AP said.
In an interview with news channel YTN, Hwang Min-hyeok, a visitor to Itaewon, said it was shocking to see rows of bodies near the hotel.
He said emergency workers were initially overwhelmed, leaving pedestrians struggling to revive the injured lying on the streets. People wailed beside the bodies of their friends, he said.
Another survivor in his 20s said he avoided being trampled by managing to get into a bar whose door was open at the alley, Yonhap news agency reported.
A woman in her 20s surnamed Park said she and others were standing along the side of the alley while others caught in the middle of the alley had no escape.
Mr Choi, the fire department chief, said that bodies were being sent to hospitals or a gym, where bereaved family members could identify them. He said most of the dead and injured are in their 20s.
“Horrific news from Seoul tonight,” British Prime Minister Rishi Sunak tweeted. “All our thoughts are with those currently responding and all South Koreans at this very distressing time.”
Jake Sullivan, the US National Security Adviser, tweeted that reports of the disaster were “heartbreaking” and said Washington “stands ready to provide the Republic of Korea with any support it needs”.
Japan's Prime Minister Fumio Kishida said on Sunday the incident left him “deeply saddened”.
“I'm hugely shocked and deeply saddened by the extremely tragic accident in Itaewon, Seoul, that took many precious lives, including those of young people with their future ahead of them,” Mr Kishida tweeted.
Witnesses described chaotic scenes moments before the stampede, with the police on hand in anticipation of the Halloween event at times having trouble maintaining control of the crowds.
Social media footage showed hundreds of people packed in the narrow, sloped alley crushed and immobile as emergency officials and police tried to pull them to free.
More than 800 emergency workers and police officers from around the nation, including all available personnel in Seoul, were sent to treat the injured.
In one section, paramedics were seen checking on a dozen or more people who were lying motionless under blue blankets.
The Seoul Metropolitan Government issued emergency text messages urging people in the area to return home.
Earlier, Mr Yoon asked officials to ensure swift treatment for those injured and review the safety of the sites. He also instructed the health ministry to sent disaster medical assistance teams and prepare beds in nearby hospitals for the injured.