A helicopter and nine boats including two tug boats and two inflatable boats searched for the survivors

AP Gilimaunk (Indonesia)

Rescuers were searching Thursday for 30 people who were missing after a ferry sank and four people died the previous night near Indonesia's resort island of Bali. As of Thursday afternoon, 31 people had been rescued from the ferry's 53 passengers and 12 crew members, the National Search and Rescue Agency said in a statement.

The KMP Tunu Pratama Jaya sank almost half an hour after leaving Ketapang port in the East Java town of Banyuwangi late Wednesday for a 50-kilometer trip to Bali's Gilimanuk port, authorities said.

A helicopter and nine boats including two tug boats and two inflatable boats searched for survivors with assistance from fishermen and people onshore. Strong waves up to 2 metres high and darkness hampered emergency responders overnight, but an official said improved weather and sea conditions on Thursday morning were assisting the search effort.

"For today's search, we are focusing on searching on the water, as the initial victims were found in the water between the location of the accident toward Gilimanuk port," Surabaya Search and Rescue head Nanang Sigit said in a statement. An officer at the port witnessed the sinking before rescuers could be alerted.

"The ferry could not be contacted via radio from the beginning. Then it could be contacted by other ships from the same company. But the ship was already in a tilting condition," Sigit said.