(CNN) -- The U.S. Coast Guard Sunday continues its search for a missing sailor whose five Texas A&M University crew mates were hoisted out of the Gulf of Mexico earlier in the day after their sailboat capsized.
Members of the Texas A&M Offshore Sailing Team are shown in this photo from the team's Web site.
The survivors -- four university students and a safety officer -- told the Coast Guard they were forced off their sailboat after it took on water and capsized.
"The flooding was so fast that the thing flipped over," USGS Capt. William Diehl told CNN.
The missing sailor has been identified by the university as Roger Stone, the vessel's second safety officer.
The sailboat, named Cynthia Woods, was one of about two dozen boats heading from Galveston, Texas, to Veracruz, Mexico, for the annual Veracruz Regatta race, which began on Friday.
Diehl said the boat was well-stocked with safety equipment -- including emergency radio beacons, life rafts and ring buoys -- but the crew could only manage to find four life jackets after the boat tipped over.
"The survivors told us that [when] they went into the water, they had four life jackets among the five, and they huddled together and they exchanged the life jacket among them so that they could stay afloat," Diehl said.
Communication with the boat was lost about midnight Friday, and the boat missed its 8 a.m. radio check the next morning, the Coast Guard reported.
A sailboat matching the description of the missing 38-foot boat was found overturned about 5:15 p.m. Saturday, authorities said.
The five survivors were found several hours later, lifted to safety by a U.S. Coast Guard helicopter around 1 a.m. and taken to University of Texas Medical Branch in Galveston for treatment.
A Coast Guard spokeswoman could not say exactly where the survivors were rescued, but said the search was focused on an area about 10 miles south of Matagorda, Texas.
Diehl said a Marine Corps C-130, a Coast Guard cutter and a man-of-war naval vessel are searching for the missing crew member. All the mariners were experienced sailors, he said.
"They were very well trained," Diehl said. "Obviously [they were] the more senior cadets at the university here, and they had very experienced safety people on board."
When rescuers retrieved the capsized boat's hull, Diehl said the keel was missing.
"That's the part that keeps the sailboat balanced in the water," he said. "And from talking to the survivors this morning, that's where the flooding started for them."
The 725-mile Veracruz regatta began on Friday and boats are expected to arrive in Veracruz on Wednesday and Thursday.