The passenger ferry was carrying 477 people and it was near the southern coast of South Korea at the time of sinking. The government officials announced that 368 people have been rescued!

The ferry, carrying mainly school students, was travelling from the port of Incheon, in the north-west, to the southern resort island of Jeju.

A major rescue effort is under way, using dozens of ships and helicopters.

According to the Korean authorities, the ship, Sewol, with the 477 passengers and crew and 150 vehicles on board, began to tilt while approaching the Jeju island , about 100 km south of the Korean peninsula.

It is not yet clear what caused the incident, but witnesses described hearing an impact, before the ship listed and quickly sank.

“We heard a big thumping sound and the boat stopped,” one passenger told the YTN by telephone. “The boat is tilting and we have to hold on to something to stay seated.”

Another told the network that at least one helicopter had reached the vessel, adding that other passengers had remained in their cabins soon after the accident but were having trouble keeping their balance.

The pupils, from Danwon high school in Ansan city near Seoul, were on their way to Jeju, a popular tourist destination, for a four-day study trip. The ship left Incheon port on Tuesday evening, according to local maritime officials, and was due to arrive at Jeju later on Wednesday.