At least 146 people were killed in a stampede on Saturday night in the South Korean capital of Seoul, fire department officials reported, with world leaders expressing their condolences to the victims.

An additional 150 people were injured in the crush, which took place in the city's Itaewon district, where Halloween festivities were taking place.

The updated death toll jumped substantially from earlier figures, which put the initial death toll at 59.

Authorities said that the number of fatalities could continue to rise, as an unspecified number of people are in critical condition.

Most of the dead are in their teens and 20s, according to officials.

What we know so far

The stampede took place around 10:20 p.m. (1320 UTC) in the popular nightclub district of Itaewon.

Choi Cheon-sik, an official from South Korea's National Fire Agency, said the crush is believed to have happened when a crowd pushed forward in a narrow alley near Hamilton Hotel. The area is a major party spot in Seoul.

South Korea's Yonhap news agency reported that at least 50 people suffered from "cardiac arrest."

Emergency services received over 80 calls from people who said they were having trouble breathing, Yonhap reported.

Over 800 emergency workers and police officers from across the country have been deployed to the capital to help treat those who were injured.

Photos from the scene appeared to show several bodies covered with sheets. Videos on social media showed fire fighters and pedestrians performing CPR on people lying on the ground.

Witnesses told local media that the streets around the site of the incident were so packed, that it was difficult for emergency services to get through to the victims.

Local media estimated that 100,000 people were in the streets of Itaewon on Saturday night for the Halloween parties. The festivities were the largest they had been in years after South Korea eased its coronavirus restrictions in recent months.

How have officials responded?

South Korean President Yoon Suk Yeol called for those who were injured to be quickly treated and also urged officials to review the safety protocols for the Halloween festivity sites.

The president also ordered the Health Ministry to deploy disaster medical assistance teams, as well as secure beds in hospitals for those who were injured. Furthermore, he oversaw an emergency meeting with other top officials over the incident.

Yoon declared a period of national mourning, adding that it was so miserable to see such a disaster happening in the heart of Seoul, Yonhap reported.

Seoul Mayor Oh Se-hoon, who was on an official visit to Europe, canceled the rest of his trip and is returning home in light of the latest news.

What has the international reaction been?

German Chancellor Olaf Scholz tweeted that the "tragic events in Seoul come as a shock to all of us."

"Our thoughts are with the numerous victims and their families," Scholz said. "This is a sad day for South Korea. Germany stands by their side."

French President Emmanuel Macron offered France's "heartfelt" support to South Korea after the tragic incident. "Heartfelt thoughts for the residents of Seoul and the Korean people after the tragedy at Itaewon. France is by your side," Macron said on Twitter.

US President Joe Biden offered his deepest condolences to the families who lose their loved ones.

"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," he said in a statement, adding that the United States "stands with the Republic of Korea during this tragic time."

British Prime Minister Rishi Sunak tweeted: "All our thoughts are with those currently responding and all South Koreans at this very distressing time."

EU foreign policy chief Josep Borrell said he was "deeply saddened" by the tragedy. "Deeply saddened by the terrible events in central Seoul. What meant to be a celebration turned into a tragedy with so many young casualties," he tweeted, adding: "We are with the people of the Republic of Korea at this difficult moment."

US Secretary of State Antony Blinken tweeted: "We send our thoughts and deepest condolences to the family and friends of the deceased and injured, as well as to the people of (South Korea) as they mourn this horrific tragedy."