Rescuers searched freezing waters for 16 missing people Thursday after a helicopter that was taking oil workers to oil rigs reported mechanical problems and ditched into the Atlantic Ocean off Newfoundland, officials said.

Of the 18 people aboard, one person was rescued and one body has been recovered. The others were missing about 30 miles out to sea, officials at a news conference said.

Rescuers pulled one person from the water with another helicopter, while the remaining 16 were still missing, officials said.

The rescued man was flown to the Health Sciences Centre in St. John's. Robert Decker of St. John's was listed in critical but stable condition.

Jeri Grychowski of the Rescue Co-ordination Centre in Halifax said a body was recovered at the same time.

Two life-rafts were spotted in the water, but rescuers later confirmed they were empty.

"The two life-rafts have been checked and there is nobody in them," said Grychowski. "They're still searching because they would have had their survival suits on."

The survival window is about 24 hours — but only if the people were wearing the required survival suits with water-activated locator beacons, said Major Denis McGuire of the Rescue Coordination Center in Halifax. The suits act like life vests and retain warmth in frigid waters.

McGuire said all rescuers have found is a debris field in a six nautical mile area.

"There has been no indication of any survivors, but the search will continue. Obviously, we'll hope for that best," McGuire said. McGuire said they'll continue to search Thursday night and on Friday.

"We'll continue to search until there is absolutely no chance that any survivors may be located."

Everyone aboard the helicopter would have been required to wear a survival suit, which are equipped with the water-activated locator beacons, but McGuire clarified earlier statements by saying that searchers didn't pick up any signals from the survival suits.

The water temperature was right at freezing. Winds are fairly strong in the area, with six- to nine-foot waves, Grychowski said.

"Intensive search operations continue to be under way for the other passengers," Prime Minister Stephen Harper said in Parliament. "Our thoughts and prayers are with the families who are anxiously awaiting word on their loved ones."

The crash came less than a month after a helicopter ferrying oil workers crashed into the North Sea off Scotland. All 18 aboard were rescued from the chilly waters after the aircraft landed upright a few hundred yards from the oil platform and was kept afloat by inflatable bags that deploy when the craft lands on water.

Rick Burt of Cougar Helicopters, the Canadian helicopter's operator, said the S-92 Sikorsky helicopter, described as no more than four years old, had the same features when it went down 55 miles (88 kilometers) southeast of St. John's, the provincial capital.

"Mechanical problems were reported, but we don't know the nature," Transportation Safety Board of Canada spokeswoman Julie Leroux said.

The pilot reported technical malfunctions and said he would try to turn back to St. John's, Burt said.

"This is a very difficult time," Burt said.

The helicopter issued a mayday call just before 8 a.m. EDT as it was headed to two oil platforms, officials said.

The crew of a Provincial Airlines aircraft flying over the area reported seeing the craft floating upside down a few minutes after the crash.

Major Paul Doucette of the Rescue Co-ordination Centre in Halifax said two planes, two helicopters and three boats are searching the debris area.

The emergency room at a St. John's hospital was being cleared for the possibility of "critically ill or hypothermic people," said Deborah Collins, a spokeswoman for the Eastern Health board.

The Hibernia oil platform is located about 200 miles east of St. John's and is owned jointly by ExxonMobil Canada, Chevron Canada Resources, Petro-Canada, Canada Hibernia Holding Corporation, Murphy Oil and StatoilHydro Canada Ltd.

SeaRose is an oil platform located in the White Rose oil and gas field, approximately 217 miles southeast of the coast of Newfoundland. The White Rose field is operated by Husky Energy and Petro-Canada.

Some residents said it reminded them of one of the worst accidents off Newfoundland, when 84 people perished when the Ocean Ranger oil rig tipped over and sank in February 1982.