A passenger on Royal Caribbean cruise ship Quantum of the Seas went overboard. JOSHUA REYNOLDS/FACEBOOK

A passenger on a Royal Caribbean cruise ship went overboard during a trip from Australia to Hawaii, a company spokesperson confirmed Wednesday to CBS News.

A Royal Caribbean spokesperson said the ship's crew is working with local authorities on search and rescue operations. Quantum of the Seas left Brisbane on April 12, and was scheduled to arrive in Honolulu on April 28.

The cruise line has not specified when or where the ship was when the guest went overboard. However, a U.S. Coast Guard spokesperson told CBS News Wednesday night that at about 11 p.m. Hawaii-Aleutian standard time on Tuesday night, it received a report of a man who had gone overboard approximately 500 nautical miles south of Hawaii's Big Island. The Coast Guard responded and conducted five searches in the course of about six hours, the spokesperson said, but the man was not located.

Another search effort would be conducted at first light on Thursday, the Coast Guard spokesperson said.

A passenger aboard the Quantum of the Seas posted about the incident on social media early on Wednesday.

"Three medical emergencies and now a man overboard," passenger Joshua Reynolds wrote on Facebook. "We have slowed down and are now turning around. Hope they are found."

CBS News has also reached out to Australian officials.

In December, a cruise passenger died after falling from the MSC Meraviglia, about 18 miles off the coast of Port Canaveral, Florida.

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