People were silent as a siren blared out for a minute, marking the beginning of the memorial service for the 304 victims who lost their lives on this day, five years ago.
Today's memorial event is taking place at Hwarang Public Garden in Ansan, near Danwon High School, where 261 of the victims were from.
Some 5,000 people, including the bereaved families and government officials took part in the event.
The nation's education minister expressed her condolences and said that she feels a grave sense of responsibility.
"Even though five years have passed, the exact cause of the tragedy still hasn't been revealed. The Moon Jae-in administration will reveal the truth at all costs and create a safer country that citizens can trust."
Musical instruments were played, and a choir sang as part of the commemorative performances.
The audience was moved to tears when one student survivor of the tragedy recited her letter to the victims.
"Dear friends, I feel that my longing for you is similar to guilt. What has separated us? The fact that you are not here to hear how sorry I am (that I survived) is so painful. But I will try to grow as a competent person so that you guys will be proud of me when we meet again."
One representative of the family members of the victims said that relatives are still suffering from traumatic memories, demanding stern punishment for those responsible.
"Our innocent children lost their lives but those responsible still haven't been punished. The state and those who had power back then, neglected their duty. We also need to bring our children back in Ansan and create a 4.16 Life and Security Park so that the country will be reminded not to repeat the same mistake ever again."
"Spring has become a reminder of the Sewol-ho incident for many South Korean citizens.
Carrying yellow ribbons, a symbol to honor the memory of the victims and their families, participants vowed not to forget the lives lost."
Kim Mok-yeon, Arirang news, Ansan.