A period of national mourning has been declared in South Korea after Saturday night's Halloween crush that killed at least 153 people and injured scores more in a packed nightlife area in Seoul. The country's president has ordered an investigation into one of South Korea's worst disasters and the world's worst stampedes in decades. Officials put the number of injured at 133 on Sunday evening, saying the death count could further rise as 37 of the injured people were in serious conditions. More than 80% of the dead — 97 women and 56 men — were in their 20s and 30s, but at least four were teenagers. On Sunday, families and friends desperately sought word of loved ones at community centers that had become makeshift facilities for missing persons. South Korea's Foreign Ministry said late on Sunday that the dead included 26 foreign nationals from 15 countries. France and Norway both confirmed that one of their country's nationals were killed. The other known foreign victims include at least four Chinese, four Russians, two Japanese, one American and at least one Iranian. World leaders expressed sadness and condolences. US President Joe Biden and his wife, UK Prime Minister Rishi Sunak, France's President Macron, German Chancellor Olaf Scholz and Italian Prime Minister Giorgia Meloni were among many to send messages. Pope Francis on Sunday offered his prayers to the victims of the crush, "young people in particular", as he addressed the faithful in St Peter's Square. Earlier, South Korea's Interior Ministry said at least 90% of the victims had been identified. On Sunday, families and friends desperately sought word of loved ones at community centers that had become makeshift facilities for missing persons. Some families wailed in grief at one center near Seoul's Itaewon district, the site of the tragedy. Announcing the mourning period, President Yoon Suk-yeol expressed condolences to the victims. "This is truly tragic," he said in a statement, extending his wishes for a speedy recovery to the many injured. "A tragedy and disaster that should not have happened took place in the heart of Seoul last night." Scenes of celebration turned to horror on Saturday night, with revelers in Halloween costumes running in panic, heart massages performed on the pavement and bodies lying in the street under makeshift shrouds. About 100,000 people, according to local media estimates, many of them very young and dressed in costumes or evening wear, had converged on the old Itaewon district to celebrate Halloween for the first time since the coronavirus pandemic began. "My friend said to me: 'something terrible is happening outside'," said Jeon Ga-eul, 30, who was in a bar at the time of the tragedy. "I said, 'What are you talking about?' I went out to see, and I saw people giving cardiac massages." The district, immortalized in the 2020 Korean TV series "Itaewon Class", is a maze of steeply sloping alleys on either side of a main avenue. "Before the accident, there were so many people pushing each other... I was caught in the crowd too. At first I couldn't get out of the way either. I felt that an accident was about to happen," Jeon Ga-eul continued. "A short person like me couldn't even breathe," an eyewitness told Yonhap news agency, adding that she survived because she was on one side of the alley. "The people in the middle suffered the most," she said. Another witness described on Twitter the panic that began when people "kept pushing down" in the sloping and already crowded alley. "More people then screamed and fell like dominoes," wrote another Twitter user. "I thought I was going to be crushed to death too as people kept pushing without realizing that there were people falling at the start of the stampede." Some witnesses said that shops in the neighborhood had stopped people from entering to escape the deadly crowd. "It seems that there were more victims because people tried to take refuge in nearby shops, but were sent back to the street because the opening hours were over," a survivor told Yonhap. Amid the crush, it soon became clear that a disaster was unfolding as social media became flooded with videos showing the densely packed crowd — and then many scenes of bodies lying on the ground as emergency crews and others tried desperately to revive them. Faced with the large number of victims, firefighters who arrived at the scene asked passers-by to help them perform CPR on the injured on the pavement amid the debris. The bodies of the crushed and trampled dead lined the ground under blankets and other improvised shrouds. Hundreds of ambulances, many from outside Seoul, lined up in the night outside Soonchunhyang University Hospital, which is close to the scene of the tragedy and to which many of the victims were transported. The stampede took place not far from the Hamilton Hotel, where the crowds of people rushed into a narrow alley. The accident was cordoned off by police and lit by the red lights of hundreds of flashing lights. Dazed, some passers-by sat on the pavement, consulting their phones. Others comforted themselves by hugging each other. Still others, seemingly unaware of the tragedy that had unfolded almost before their eyes, continued to party. "It's very sad, something we didn't expect at all. I never thought something like this could happen in Korea, especially in Itaewon," said Juyoung Possamai, a 24-year-old Brazilian working in the area. "I've been to many Halloween parties in Korea, there are always a lot of people but nothing like this has ever happened. This is something I will never forget." — Euronews