Indonesian rescue services saved over 240 people who were aboard a crowded Indonesian passenger ferry that sank on Nov. 22 in rough waters off the Island of Sumatra.

The accident claimed the lives of 29 people and at least 17 others are still missing, according to Indonesia ’s Antara news agency.

The ill-fated ferry, the Dumai Express 10, was sailing the Batam-Bengkalis-Dumai route when it sank in the Karimun waters, reported the news agency, adding that the cause of the accident is still unknown.

However, the agency cited Basri Muhammad, a former sailor as saying that he believed that the vessel had sank after it being hit by enormous waves. The waves in the Karimun waters at the time were believed to be almost six meters high.

Rescuers are still searching the area for survivors./.