A South Korean ferry capsized off Jindo island, off the southwest corner of the Korean peninsula, on April 16 in what could be the country's worst maritime accident in two decades.
The ferry had around 475 passengers on board, according to Reuters, 340 of which were reportedly students and teachers from the Danwon High School in the city of Ansan, just south of Seoul. The ship was headed to the resort island of Jeju for a school field trip.
While rescue efforts are still underway, about 25 people have been confirmed dead and 271 are still missing.
—By CNBC's Nyshka Chandran. Updated April 18 2013.
No immediate causes have been revealed as to why the 6,825 ton vessel sank en route to its destination.
Crew members of a local government ship involved in the rescue efforts told Reuters the surrounding area was free of reefs or rocks and said the accident may have been caused by a malfunction on the ship.
The ferry sent a distress signal around 9am local time on Wednesday, according to the coastguard, which triggered a rescue operation involving 100 coastguard and navy vessels as well as 18 helicopters. A U.S. navy ship that was conducting routine patrol in the area has also joined the search effort.
Speaking to local media agency Yonhap News, 58-year old survivor Kim Hong-kyon said students were tumbling in all directions after hearing "a loud thumping sound," followed by a lurch to one side of the boat.
A member of the South Korean Coast Guard is pictured observing the site of the sunken ferry. The 264-mile journey from the port of Incheon in Seoul to Jeju island is one of the most common routes in South Korea.
The vessel - named Sewol, which means "time and tide" in Korean - belonged to a company by the name of Chonghaejin Marine based in the northwestern city of Incheon. Company officials have since offered an apology but declined to comment further.
In a statement on the website of her office, President Park Geun Hye said that "I feel terrible that this unfortunate accident has happened to students on a field trip, and other passengers. If there is any hint of survivors, make every effort and never give up until the end."
Family members of passengers on board the capsized ferry arrived at the port of Jindo late Wednesday and early Thursday where they await news about the rescue efforts.
According to Reuters, some frustrated families took matters into their own hands on Wednesday night, hiring their own boat to travel to the scene.
A listof survivors has been posted at Jindo port and continues to be updated throughout the day.