On Saturday night, more than 150 people, mostly young adults in their 20s and 30s, were killed in South Korea’s capital Seoul, when an estimated 100,000 people surged into a narrow alley of Itaewon, the nightlife district in Seoul for the country’s biggest Halloween festival. As of Sunday evening, officials said 153 people were killed and 133 were injured. At least 20 foreigners from China, Russia, Iran and elsewhere were dead. U.S. State Department said two American college students were among the dead. On Sunday, South Korean President Yoon Suk Yeol declared a week-long national mourning period.