Hundreds of Indonesian rescuers, police officers and navy divers are searching the Java Sea for 128 people still missing after the passenger ship KM Virgo Transport 8 capsized over the weekend, authorities said Monday.

The vessel was carrying 243 people when it departed Surabaya for Banjarmasin on Saturday. Early Sunday, the captain reportedly warned the operator about rough weather and said the ship was tilting. Communication was later lost, and the vessel was found overturned about 150 km from its destination.

Indonesia’s National Search and Rescue Agency (BASARNAS) said 115 people had been accounted for, including six confirmed dead. More than 600 rescue personnel have been deployed, according to BASARNAS chief Mohammad Syafii.

“We are hopeful that we will be able to find survivors,” Syafii said.

Rescue efforts received a boost after a 28-year-old woman was found drifting at sea and rescued. BASARNAS said she was evacuated by helicopter and taken to hospital.

Survivors reported that large waves flooded the ship before it capsized. Syafii said the waves may have been more than three meters high, but authorities stressed that the exact cause of the accident remains under investigation.

The National Transportation Safety Committee is also assisting investigators by collecting information and evidence, according to BASARNAS.

Sources: Reuters, via Arab News; ANTARA News; BASARNAS.