A local office of the Japan Coast Guard said it has arrested the captain of a small vessel for negligence resulting in his ship hitting a reef and sinking in the Seto Inland Sea the previous day.

Yosuke Tada, 45, has admitted to the charge. The incident, which took place off Kagawa Prefecture on Thursday, threatened the lives of 52 schoolchildren and others aboard who had to be rescued by coast guard and fishery vessels as the ship went under.

Tada's ship, the 19-ton Shrimp of Art, struck the reef at around 4:40 p.m. The Takamatsu Coast Guard Office on Friday confirmed a rupture in the bottom of the vessel through which seawater is believed to have flowed inside, causing the vessel to sink.

When Tada reported the accident to the coast guard office, he said he thought the ship had hit a floating object, while also stating it might have bumped a rock.

A total of 62 people were on board at the time, including the group of 52 sixth graders on a two-day excursion from their school in the same prefecture. While two of the students were taken to a hospital for hypothermia and hyperventilation after the accident, all of them returned home later in the day.