South Korean Prime Minister Han Duck-soo vowed on Monday to conduct a thorough investigation into the stampede that killed more than 150 people during Halloween over the weekend in Seoul's Itaewon district.

Officials said 154 had been killed and 149 injured, with 33 people in serious condition. The latest Yonhap News Agency report said that 26 foreigners from 14 countries were among the dead, including four from China.

The government will do its best to improve the necessary systems to prevent such an event from reoccurring, Han said during a live broadcast.

Tens of thousands of people had crowded into narrow streets and alleyways of Itaewon on Saturday for the first virtually unrestricted Halloween festivities in three years. Many of the revelers were in their teens and dressed in costume.

But chaos erupted when people poured into one particularly narrow and sloping 3.2-meter-wide alley, even after it was already packed, according to Yonhap. "Some of them began to fall over, causing others to fall down like dominoes and pile up on one another," it added.

South Korean President Yoon Suk-yeol, who has declared a period of national mourning and designated Itaewon a disaster zone, visited a memorial altar near the Seoul city hall and paid his respects to victims with first lady Kim Keon-hee on Monday, his office said.

Chinese President Xi Jinping sent a message of condolence on Sunday to Yoon over the Halloween tragedy.

Other world leaders including U.S. President Joe Biden, British Prime Minister Rishi Sunak, Russian President Vladimir Putin, Japanese Prime Minister Fumio Kishida, Canadian Prime Minister Justin Trudeau, German Chancellor Olaf Scholz, French President Emmanuel Macron and Ukrainian Foreign Minister Dmytro Kuleba have also sent condolences to South Korea after the deadly crush.

(With input from agencies)

(Cover: Flowers are offered for victims near a scene of crowd surge accident where lots of people fell at Itaewon area in Seoul, South Korea, October 30, 2022. /CFP)