Indonesian rescuers searched Monday for more than 100 people missing after a ferry capsized in rough seas, with aircraft, naval vessels and divers deployed to find survivors, the country’s top rescue official said.

The Virgo Transport 8, which authorities said carried 213 passengers and 30 crew, lost contact with its shipping company early on Sunday after departing Surabaya, Indonesia’s second-largest city, in East Java.

National search and rescue agency chief Mohammad Syafii said Monday that six people had been confirmed dead and and 129 others were missing.

At least 108 others had been rescued the previous day.

Five aircrafts and 17 vessels, including navy warships, were deployed to assist with the search, which will be focused in areas around the capsized ferry, he added.

“We will maximise the search operation in six sectors that we have divided by prioritising the search for floating victims,” Syafii said.

“Hopefully, we can find the victims in safe condition.”

He added that divers and underwater drones will be deployed to search for the victims in and around the wreck, which rescuers have located.

The ferry was not overloaded and it transported passengers below its maximum capacity of 500 people, Transportation Minister Dudy Purwagandhi said in a press conference Monday.

Marine accidents are a regular occurrence in Indonesia, an archipelago of more than 17,000 islands that relies heavily on boat connections for daily transport and tourism.

Lax safety standards and unpredictable weather are the main reasons for the disasters.

Last week, a speedboat carrying eight people, including five journalists working for local and international news agencies, went missing near a volcano, Mount Anak Krakatau, in Banten province. That search is ongoing.