Passengers were crowded on the left side of the top deck of a whale-watching boat when it was struck by a wave from the right side, causing the vessel to roll over and capsize, sending 27 people into the water off Vancouver Island's west coast, an investigator said.
Five British nationals were killed, and the search continued for a missing Australian man. Twenty-one people were rescued after the Leviathan II capsized Sunday afternoon.
Marc Andre Poisson, Director of Marine Investigations for Canada's Transportation Safety Board, on Tuesday released preliminary results of the investigation into the accident.
Affecting 'vessel's stability'
"We know that most passengers were on the top deck on the port side, that's the left side of the vessel. This would have raised the center of gravity, affecting the vessel's stability," Poisson told a news conference in Tofino.
"We also know that the sea conditions were such that a wave approached from the starboard quarter, that's the right of the vessel. We know that the vessel broached and then capsized," he said.
Poisson said investigators have now interviewed the three crew members and some of the passengers. One life raft deployed and was used, he said. The full investigation is expected to take months.
The British Columbia Coroners Service identified the five victims, two of whom were British nationals living in Canada. They are David Thomas, 50, and his 18-year-old son Stephen, from Swindon in southern England; Katie Taylor, 29, of Whistler, British Columbia; Nigel Francis Hooker, 63, of Southampton, England, and Jack Slater, 76, of Toronto.
Rupert Potter, the British consul general based in Vancouver, said earlier Tuesday that the deaths are a tragedy that is resonating around the world. While in Tofino, he met with relatives of those who died.
"It has clearly deeply affected those involved," he said. "It's affected the community here in Tofino and it's affected people back in the U.K."
Potter shook hands with B.C. Premier Christy Clark and expressed his thanks for the support he and the victims' families have been receiving.
In Britain, the Down Syndrome Association UK said in a statement that David Thomas was a "huge supporter" of the organization and "one of the driving forces behind the Swindon Down's Syndrome Group, where he was a trustee."
Stephen Thomas, who had Down Syndrome, "was a very talented young man and a gifted photographer," the association said in a statement.
"His love of photography started when he was eight years old. We were all delighted when Stephen's beautiful image Moraine Lake won the national My Perspective photographic competition last year," the association said.
"All of our thoughts and condolences are with the Thomas family at this terrible time," the group added.
Microsoft UK said David Thomas was an employee.
"Our thoughts and deepest sympathies are with their family, friends and David's colleagues and we will be doing everything we can to support them," the company said.
David Thomas' wife, Julie, was rescued and is hospitalized with minor injuries.
'Larger than life'
Michele Slater Brown, of Milton, Ontario, said she was notified about her father's death "in the wee hours this morning," and called him "larger than life, a charmer, handsome, entrepreneur, engineer in the navy ... and a lovely dad."
Coroner Matt Brown said a preliminary investigation suggests those who died were on the top part of the boat and that they weren't wearing life-jackets because it's not required in the type of vessel they were in.
Investigators will review the weather, wreckage and the maintenance history of the 20-meter (65-foot) boat to determine why it capsized, Poisson said.
He also said they will try to recover the boat's electronics on Wednesday to further the investigation.
A senior employee of Jamie's Whaling Station, the company operating the boat, said the vessel sank so quickly the crew didn't have time to issue a mayday call.
Rescued by locals
The crew shot flares from the water which attracted the attention of local aboriginal fishermen who rushed to help rescue people, said Corene Inouye, the company's director of operations.
Clark, the B.C. premier, said she was horrified and heartbroken when she heard about the capsized boat, but she's proud of the way British Columbians came together to help.
"The Ahousaht First Nation, the people of Tofino, the people who know this coast so well, when there was a crisis, when there were lives at risk, people stepped up and stepped in and saved lives," Clark said, as she thanked the community.
The boat capsized about 8 nautical miles (14.7 kilometers) off Tofino, a popular destination for whale watchers that is at the very tip of a peninsula about 320 kilometers (200 miles) northwest of Victoria, the capital of British Columbia.
Australia's Department of Foreign Affairs and Trade on Tuesday confirmed that an Australian man was missing.
Australian Associated Press reported that the 27 year-old Sydney man's family said he was on the boat with his girlfriend and her family when it sank. His girlfriend's father was among the dead, AAP said.