(Updates throughout with new details, quotes.)
OTTAWA (AFP)--One person has been hospitalized, another is dead and 16 were missing at dusk after a helicopter ferrying workers to an oil rig crashed Thursday into the icy North Atlantic off the Canadian coast.
The helicopter was flying from Saint John's, Newfoundland to the Hibernia offshore oil platform when it plunged into the ocean some 55 kilometers (35 miles) southeast of Saint John's, said officials.
It had started to turn around because of "technical problems" when the pilot sent out a distress call, said Major Denis McGuire of the Joint Rescue Coordination Center in Halifax.
At 9:18 a.m. (1148 GMT) the helicopter hit the water, he said.
One person was plucked from the frigid ocean by a second charter helicopter and rushed to a hospital in Saint John's, and a body was recovered.
Two life rafts were also found empty at the scene. The helicopter had overturned and quickly sank 120 meters (400 feet) to the bottom.
Canada's Prime Minister Stephen Harper said in the House of Commons the helicopter's downing was a "tragic accident," and vowed a search for the remaining 16 passengers and crew would continue.
As he spoke, two military aircraft and two Coast Guard vessels were preparing to search for survivors well into the night and all day Friday.
"At this time there's no indication of what happened," McGuire told a press conference.
"All we've got is the debris field" that stretches 11 kilometers (seven miles) on the ocean surface, he said. There were "no indications of any survivors."
But, he added: "We'll continue to search until there's absolutely no chance that any survivors might be located.
"And we obviously hope for the best."
A healthy 30-year-old in a dry suit could survive 24 hours in this water, he added.
Weather at the time of the accident was mild.
As rescuers continued to comb the area, however, the weather quickly deteriorated. Winds picked up, creating waves up to three meters (nine feet) high, and water temperatures were near freezing.
The search would be "more difficult" at night, said McGuire.
Searchers would drop flares to illuminate the ocean surface and use night vision goggles to try to spot any of the colorful survival suits the missing passengers were thought to have been wearing.
"We identify search patterns that we use that ensure that the entire area is covered and we do a drift assessment to determine where anything on the surface would have drifted," said Rick Burt of charter firm Cougar Helicopters.
The chopper was part of Cougar Helicopter's newer fleet of Sikorsky S-92 helicopters, which averaged four or five daily trips to and from the oil rig, 315 kilometers east of Saint John's, he said.
The oil platform is the world's largest, with storage tanks for 1.3 million barrels of crude oil. It is owned by a joint venture involving Petro Canada, ExxonMobil, Chevron, and others.
Since the accident, Cougar Helicopter said it has temporarily suspended all of its offshore flights until it knows the cause of the crash.