TAMPA, Fla. (AP) — The Coast Guard was searching Gulf of Mexico waters Monday for an 18-year-old recent high school graduate from Louisiana who is believed to have gone overboard from a cruise ship.

Bruce O’Krepki went overboard from the Carnival Fantasy at about 9:45 p.m. Sunday, about 150 miles southwest of Tampa, the Coast Guard said.

O’Krepki is from Hammond, La., where The Daily Star newspaper reported that he recently graduated from St. Thomas Aquinas High School. He was with about 35 classmates on the ship.

His uncle, Rick O’Krepki, said Monday afternoon that the family had no details about what happened.

‘‘We are awaiting more word,’’ O’Krepki told the newspaper. ‘‘Hopefully, the brave men and women of the U.S. Coast Guard will be successful in searching for Bruce.’’

He asked that the family’s privacy be respected and for people to keep his nephew in their thoughts and prayers.

A search plane, helicopter and Coast Guard cutter were sent out to search.

The ship had left New Orleans and was en route to Key West.