SEOUL, South Korea >> South Korean officials said today they’ve found many fragments of suspected human bones from a ferry that was retrieved three years after it sank, killing more than 300 people.

Most of the 304 dead were high school students on a field trip and nine bodies haven’t been recovered yet. The ferry Sewol was raised and transported to a port in March. Workers haves since found four pieces of suspected human bones, three from the recovered ferry and one from its sinking site.

The Oceans Ministry said its search team found “many” more such bone fragments today from the ferry’s stern parts but didn’t say how many. The area is close to a room where many female students stayed at the time of the April 2014 sinking, according to local media reports.

Ministry officials said about one month of DNA tests is needed to confirm whether the remains belong to any of the missing victims. The bone pieces recovered earlier this month were under similar DNA tests, the officials said, requesting anonymity because of department rules.

The government in March said it had found bones believed to be from missing victims before correcting they belong to animals.

The Sewol’s sinking, one of South Korea’s deadliest maritime disasters, triggered a rare outpouring of national grief and outrage over a botched rescue works.

The public anger later contributed to the ouster of President Park Geun-hye, who was removed from office and arrested in March on corruption charges. Her liberal rival Moon Jae-in, who has taken the initiative in criticizing Park over the sinking, took office earlier this week after winning the election.