South Korea's President Yoon Suk-yeol declared a period of national mourning on Sunday after a Halloween crush killed some 151 people in a packed nightlife area in Seoul.
Yoon expressed condolences to the victims, mostly teenagers and people in their 20s, and his wishes for a speedy recovery to the injured.
"This is truly tragic," he said in a statement. "A tragedy and disaster that should not have happened took place in the heart of Seoul last night."
A huge crowd celebrating in the popular Itaewon district surged into an alley on Saturday night, emergency officials said, adding the death toll could rise.
Choi Sung-beom, head of the Yongsan Fire Station, said 151 deaths had been confirmed, including 19 foreigners. He told a briefing at the scene 82 people were injured, 19 of them seriously.
It was the first Halloween event in Seoul in three years after the country lifted COVID restrictions and social distancing. Many of the partygoers were wearing masks and Halloween costumes.
"A number of people fell during a Halloween festival, and we have a large number of casualties."
Choi Sung-beom
Many of those killed were near a nightclub, and many were women in their twenties, Choi said.
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.
One woman heard on a social media post cries out in English: "Oh my God, oh my God, Jesus fucking Christ."
Other footage showed chaotic scenes of fire officials and citizens treating dozens of people who appeared to be unconscious.
A Reuters witness said a make-shift morgue was set up in a building adjacent to the scene. About four dozen bodies were carried out later on wheeled stretchers and moved to a government facility to identify the victims, according to the witness.
Worldwide condolences
US President Joe Biden and his wife sent their condolences and wrote: "We grieve with the people of the Republic of Korea and send our best wishes for a quick recovery to all those who were injured."
British Prime Minister Rishi Sunak tweeted: "All our thoughts are with those currently responding and all South Koreans at this very distressing time."
First Halloween event in three years
It was the first Halloween event in three years after the country lifted COVID restrictions and social distancing. Some witnesses described the crowd becoming increasingly unruly and agitated as the evening deepened.
The Itaewon district is popular with young South Koreans and expatriates alike, its dozens of bars and restaurants packed on Saturday for Halloween after businesses had suffered a sharp decline over three years of the pandemic.
"You would see big crowds at Christmas and fireworks...but this was several ten-folds bigger than any of that," Park Jung-hoon, 21, told Reuters from the scene.
Curfew on bars and restaurants and a limit of 10 people for private gatherings were lifted in April. An outdoor mask mandate was dropped in May.
President Yoon Suk-yeol presided over an emergency meeting with senior aides.
"The area is still chaotic so we are still trying to figure out the exact number of people injured," said Moon Hyun-joo, an official at the National Fire Agency.
Foreigners were among those transferred to nearby hospitals.
Authorities said they were investigating the exact cause of the incident.