SEOUL -- South Korean President Yoon Suk-yeol on Sunday declared a period of national mourning after a crowd surge left at least 153 people dead and 82 injured during Halloween festivities in Seoul.
Two Americans were among the 19 foreign nationals who died, ABC News confirmed. The victims were largely in their 20s and many were transferred to local hospitals in cardiac arrest after emergency CPR, according to the National Fire Agency.
The national mourning period for the victims will go from Sunday through Saturday, Nov. 5, Yoon said.
The incident was reported Saturday night at around 10:20 p.m. local time, officials said.
The crush took place in the nightlife district of Itaewon. Tens of thousands of people were believed to have gathered in Itaewon for festivities on Saturday night. Witnesses said the streets were so densely clogged it was practically impossible for emergency workers and ambulances to reach the alley near the site. People were on top of each other for more than an hour.
Nathan Taverniti, a 24-year-old from Australia, who is visiting friends in Seoul, said he was at the site with three female friends. One of those friends died and another was in critical condition and told by the doctor she was not going to make it, Taverniti said. The third one was hospitalized and is now with family, he said.
Taverniti told ABC news that people were going up and down a small alley hill at the same time, when some people fell down and then people started to pile up on each other.
"Because the whole street in front of me was just people lying down on the floor, and I could see my friend's hand, and I grabbed her hand and said, 'I'm going to get you out,' but she already wasn't breathing," Taverniti told ABC News.
More than 100,000 people gathered for Halloween parties in the area, which is known for its nightclubs. The area has bars located along narrow back alleys that flank the main street. People got stuck in these curved, slanted alleys, according to witnesses.
Witnesses also said they didn't see a police presence in Itaewon at the time of the incident.
World leaders have offered their condolences and messages of support following the South Korea tragedy. President Joe Biden extended his sympathies Saturday on behalf of himself and first lady Jill Biden.
"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," the president said in a statement. "The Alliance between our two countries has never been more vibrant or more vital -- and the ties between our people are stronger than ever. The United States stands with the Republic of Korea during this tragic time."
Japanese Prime Minister Kishida Fumio issued a statement expressing his country's solidarity with South Korea and its citizens.
“I am greatly shocked and deeply saddened by the loss of many precious lives, including young people with a bright future, as a result of the very tragic accident that occurred in Itaewon, Seoul," the minister said. "On behalf of the Japanese government and people, I would like to express our heartfelt condolences to those who lost their lives and their bereaved families, and we pray for the speedy recovery of the injured people.”
ABC News' Meredith Deliso, Joanne Aran and Anthony Trotter contributed to this report.