Carnival Cruise Lines said witnesses saw a man jump overboard during a cruise out of Galveston.
The Carnival Conquest returned to Galveston without one of its passengers Sunday.
Shortly after the ship left Cozumel, Mexico, on Friday, the cruise line said a 39-year-old man jumped overboard.
"I was walking from deck 8 up to 9 to get a soda, and I could hear this awful screaming from one of the passengers on my floor," said Jonathan Wang, of Sugar Land.
He was on board the Conquest when the ship abruptly stopped about 6:30 p.m. Friday.
"The boat made a series of maneuvers and we immediately saw a few other boats in the area -- small boats that we could only assume were helping in the search," Wang said.
Carnival Cruise Lines said, "All appropriate authorities were notified and the ship returned to the location where the man was last seen to begin search and rescue operations. The Carnival Conquest was later released from the search while Mexican authorities continue the search and rescue efforts."
The cruise line also said the on-board team assisted the missing man's family.
The Carnival Conquest left the Port of Galveston Sunday night on another seven-day cruise to Jamaica, Grand Cayman and Mexico.