When he arrived in the city of Seoul, South Korea in late August, American exchange student Steven Blesi quickly developed a wide circle of friends from around the world.   

  The 20-year-old from Atlanta was studying at the city’s Hangyang University as part of a US study abroad program.  He had planned to meet up with several people from the class on Saturday in Seoul’s Itaewon district to celebrate Halloween with thousands of other young revelers.   

  But when he didn’t turn up, his friends and family launched a frantic search to find him, before eventually learning he had died in a stampede in an overcrowded alley that killed 156 mostly young people.   

  Blesi’s best friend in the program was Ian Chang, 21, from Florida, who was also his college dorm roommate.   

  “We like a bit of adventure, doing spontaneous things,” Chang told CNN in an exclusive interview this week.  “And just exploring the city.”   

  Blessy loved “dancing, drinking, partying,” Chang said, and “every time he met someone new, it had a big effect on him.”   

  On Saturday night, Chang and Blesi were supposed to meet in the narrow streets of Itaewon, a popular district full of nightclubs, bars and fast food outlets.  The pair had been together earlier that day, when Chang had gone home to change.   

  “At first we just wanted to go to Itaewon to see what it was like, see what’s so special about Halloween there,” Chang said.  “Because we heard from people (that) Itaewon will be big on Halloween.”   

  But when he arrived in Itaewon around 9:40 p.m., Chang began to realize the danger that was unfolding.  She sent Blesi a Snapchat message at 10:17 p.m., asking him to avoid Itaewon and meet in Hongdae neighborhood.   

  “It’s very crowded.  And there’s nowhere to go,” Chang’s message said.   

  As news of the horror that unfolded in Itaewon Strait spread over the next few hours, Blesi’s other friends also tried to call and text him.   

  “You can come to my place… it’s safe here.  Where are you Steven?’  messaged 24-year-old Belgian exchange student Wassim Essebane around 1 a.m. Sunday through KakaoTalk, a South Korean messaging app similar to WhatsApp.   

  Another friend, Stefanie Reuss, 22, was also trying to locate Blesi from her home, more than 8,000 kilometers (4,970 miles) away in Austria.  Royce helped raise the alarm, posting messages on Instagram and Twitter trying to find him.   

  One of the people Reuss contacted was 19-year-old Olivia Kim of Houston, Texas, who had been dating Blesi for a few weeks.  Kim planned to go to Itaewon on Saturday night, but changed plans at the last minute.  She was supposed to go on a date with Blessis on Sunday afternoon.   

  “Steven and I talked almost every day for about a month after our first date in early October,” Kim told CNN.  “I immediately loved his emotional generosity, wit, adventurous spirit and upbeat personality.”   

  Kim had lost contact with Blesi on Saturday and when he still hadn’t responded on Sunday morning, she became concerned that he was one of the victims.   

  Back home in Atlanta, Blessy’s father, Steve, was also becoming increasingly desperate.   

  “Maybe half an hour before this tragedy happened, I sent him a message on WhatsApp… “I know you are out.  Stay safe.  I love you.’  And I never got an answer,” said Blessi’s father.   

  Over the next few hours, repeated missed calls and messages went unanswered.   

  Around 6 a.m. Sunday, Chang said Blessy’s mother emailed him, seeking help locating her son.  Chang said they tried calling hospitals in Seoul, enlisting their Korean-speaking friends to help.   

  But around noon on Sunday, they all got the news they feared the most after being told by Blessi’s father, who had been informed by the US embassy.   

  Another American student from the program, 20-year-old Anne Gieske from Kentucky, also died in the crowd crush on Saturday night.  She was with Blessis earlier in the evening, although it is not clear if they were together when they died.   

  Earlier in the evening, young partiers had thought the crowded streets in Seoul’s Itaewon district were part of the fun of the Halloween experience.   

  “At first we thought it was a joke,” said Anne-Lou Chevalier, a 22-year-old French exchange student who survived the crowd crush.  “We heard Halloween in Itaewon was amazing.”   

  But when an estimated 100,000 people eventually crammed into the narrow lanes and alleys, panic set in.   

  “We started to be very, very stuck and devastated, and then we heard some people screaming and crying,” Chevalier said.   

  “We were trying to help people, because there were a lot of people (who) couldn’t breathe,” said her friend, 18-year-old Alice Sannier, also from France.   

  The friends were separated in the chaos of the crowd and Chevalier passed out twice in the crash, adding that he felt “like he was dying”.   

  “I remember I had no air, so I started suffocating,” Chevalier said.  “I kind of got evacuated with my boyfriend, so I’m very, very lucky.”   

  The two friends said their slight frames made them more vulnerable.   

  “Because we’re small in size, there (were) a lot of foreigners who were (much) taller and surrounding us, so at some point you can’t get some air and then you start freaking out,” Chevalier said.   

  In total, 101 women and 55 men were killed in the disaster.   

  Sannier and several other witnesses who spoke to CNN said they saw several people being pushed into the crowd, which is being investigated as a possible trigger for the domino effect that occurred.   

  “Everybody was pushing, that’s why so many people were dying,” Sannier said, adding that they didn’t see any police when they were in the crowded alley.   

  Records show that eleven calls had been made to the police to warn of the situation in Itaewon before the crash on Saturday night, and the head of South Korea’s National Police Service said the police response to those calls was “inadequate ».  An investigation is underway.   

  Friends and families of the victims are just beginning to process what happened to their loved ones, many of whom were just beginning their lives.   

  “It’s unthinkable,” Royce told CNN.   

  Reuss had met Blesi when he spent three weeks traveling in Seoul in September.  They had become fast friends, partying together, doing karaoke and eating Korean BBQ, and making plans to travel to Europe together.   

  “He was curious about the world,” Reuss said.  “He had so many dreams.  I look a lot like him.  It saddens me.”   

  Blessy’s father said his son “has always been an adventurer.”  He was an Eagle Scout, liked basketball and wanted to learn several languages, he said.   

  “He had an incredibly bright future that is now gone,” he added.   

  One of Blesi and Chang’s most recent adventures was a hiking trip a few weeks ago on the mountainous island of Jeju, off the southwest coast of South Korea.   

  “We’re all impressed by how far we’ve come from home,” Chang said.  “In all these adventures together.  And to explore something that we probably wouldn’t have thought of a year ago.”   

  In addition to hiking and enjoying South Korea’s food and nightlife, Blesi also loved its cultural traditions.   

  “He had never been to Asia, so he really wanted to explore,” Chang said.  “He was very excited about going to, say, temples.”   

  Essebane’s friend told CNN that Blesi was “an absolutely wonderful guy.”   

  “He was kind, open, made you feel comfortable, had such a warm personality and was funny,” Essebane said.  “I will never forget him.”   

  In just a few months of knowing each other, Chang said he had come to think of Blessy as his “brother.”   

  “Steven was the kindest person ever,” Chang said.   

  “I’m just happy to have had him in my life,” he added.  “I wish I could have made more memories with him.”