More than 150 people were killed in a stampede at a Halloween event in central Seoul, officials said Sunday, with South Korea's president vowing a full investigation into one of the country's worst-ever disasters.
The crowd surge and crush hit in the capital's popular Itaewon district, where estimates suggest as many as 100,000 people -- mostly in their teens and 20s -- went to celebrate Halloween on Saturday night, clogging the area's narrow alleyways and winding streets.
President Yoon Suk-yeol declared a period of national mourning Sunday, telling the country in a televised address that "a tragedy and disaster occurred that should not have happened".
He said the government "will thoroughly investigate the cause of the incident and make fundamental improvements to ensure the same accident does not occur again in the future.
"My heart is heavy and it is difficult to contain my sorrow," he added, before he visited the scene of the disaster and spoke to emergency workers.
Seoul mayor Oh Se-hoon, who rushed back to South Korea from a work trip in Europe, said his office would set up a memorial altar at Seoul Plaza so the public could pay their respects to the victims, starting Monday morning.
"Most of the casualties are young people like our sons and daughters, which makes it even more sad," Oh said while visiting the site of the disaster.
Narrow, sloping alleyway
Eyewitnesses described being trapped in a narrow, sloping alleyway, and scrambling to get out of the suffocating crowd as people piled on top of one another.
Seoul's interior ministry told the AFP news agency that 153 people had died, including 20 foreigners, in the stampede, which occurred around 10:00 pm local time.