ofion British Columbia Reuters

A Canadian whale-watching tour boat with 27 passengers on board sank off the coast of British Columbia on Sunday, killing five people with one missing, rescue officials said.

Twenty-one people had been rescued when the search was called off late at night, Melissa Kai, a spokeswoman for the Joint Rescue Coordination Centre (JRCC), said.

A military rescue helicopter and plane had been sent to the waters off the coast of Tofino after the vessel sent a distress signal around 5 p.m. local time, according to the JRCC. Several other coast guard vessels were involved in the search off the rugged west coast of Vancouver Island. Military planes and coast guard vessels lit up the area where the vessel remained partially submerged, eight nautical miles (15 km) northwest of Tofino.

Tofino, a community of roughly 2,000 people on the west coast of Vancouver Island, is a popular tourist destination for surfers, hikers and whale watchers from around the world.

John Forde, who works at another ecological tourism company, said passengers on a vessel like the Leviathan II, a three-deck 65-foot cruiser that can carry up to 46 people, would not have to wear life jackets. The boat, like ferries, would only be required to have life jackets on board.

"The sea was three to four meters, a fairly big sea, but not much wind or too unusual for the conditions we deal with on a regular basis out here," Forde, who took part in the rescue for several hours, told Global television.