Four people have been confirmed dead with two critically injured after a tour boat with 27 passengers on board sunk off the coast of British Columbia. The area is popular for whale watching tours.

British Columbia Ambulance Service said that there are four confirmed fatalities and two patients have been flow to nearby hospitals in critical care. An additional 18 people were treated at the Tofino General Hospital. Some have been discharged while others can be expected to leave the hospital later.

The first pictures of the capsized boat was taken by Albert Titian who was among the first from Ahousaht First Nation at the scene,

An unknown number of people are still unaccounted for, Gobalnews reported. The tour vessel, The Leviathan II, a 65-foot cruiser, sunk near Tofino. The vessel is operated by a local company Jamie's Whaling Station and Adventure Centres.

The Leviathan II is now partially submerged eight nautical miles northwest of Tofino, a small town of 1,876 residents on the west coast of Vancouver Island. Early reports say that members of the Ahoushat First Nation saw a flare and quickly responded and managed to rescue a number of the passengers.

Local fishermen in the area say that Plover Reefs, where the boat capsized, can be like a "washing machine". An initial statement from the Joint Rescue Victoria Coordination Centre in Tofino said: "There are fatalities involved and survivors. We are also conducting a search to confirm that we have recovered everybody," the rescue centre said. The centre confirmed that the vessel made a mayday call shortly before 4pm on Sunday (25 October) near Tofino.

The Coast Guard is expected to provide an update later in the evening. Jamie's Whale Watching has confirmed that the boat belonged to the company but declined further comment. "I hope you can understand that all of our focus and energy is on the passengers and crew right now and we don't have any information and we will be releasing it when the time is appropriate," an employee told the Canadian Press.

According to Global News, a boat operated by Jamie's also sank near Tofino in 1998, killing a German tourist and the captain of the ship. This could not be immediately independently verified.

On its website, the company describes the Leviathan II as "Tofino's largest and most comfortable whale watching vessel." It has three decks with the option of sitting inside or outside and can accommodate up to 46 passengers.