About 100 people are feared trapped inside a ferry that sank off Papua New Guinea with more than 350 people on board.
So far, nearly 250 people have been rescued from the sea off PNG's northeast coast, according to numerous news reports.
The MV Rabaul Queen, a 22-year-old Japanese-built ferry, sank Thursday about nine nautical miles off the PNG coast after being hit by three large waves, ABC Australia's News24.com reported, citing Australia's Maritime Safety Authority (AMSA).
Australia, PNG's nearest neighboring country, is heavily involved in the rescue effort.
"Updated reports from the five rescue vessels indicate there were approximately 246 survivors recovered [on] Thursday," AMSA said. "PNG officials are processing the survivors on arrival in Lae," PNG's second-biggest city.
Sky News interviewed survivors brought to Lae's Angau hospital, quoting Alice Kakamara, 30, as saying: "We were in the top deck, first class. The sea was really rough, windy, big waves. The boat tilted once, then twice then three times and it went over. There was oil everywhere."
Doctors at the hospital said survivors were being treated for inhalation of toxic substances during their escape from the wreck.
The BBC cited an official as saying there were fears people had been trapped inside the ferry when it sank. Ships, planes and helicopters were involved in ongoing rescue efforts.
The ferry operator, Rabaul Shipping, said the ferry had been traveling between Kimbe on the island of New Britain to the coastal city of Lae on the main island, and the captain had routine radio contact with another vessel not long before the sinking.
"There appeared to be no indications of distress during this communication," it said, according to ABC's News24.
Meanwhile, staff at the Rabaul Shipping offices in Kimbe had to be evacuated from the Kimbe office by police to a secret location after a crowd that had gathered for any news became rowdy and began throwing rocks, News24 reported.
"We are stunned and utterly devastated by what has happened," Rabaul Shipping managing director Peter Sharp reportedly said. "We acknowledge that this has caused tremendous suffering. Our condolences go to the loved ones of those affected."
PNG Prime Minister Peter O'Neill has reportedly ordered an investigation.