Rescue officials say five are dead after a tour boat carrying 27 people capsized off the coast of Tofino, B.C. on Sunday.

A search-and-rescue mission was launched after the vessel made a mayday call shortly before 4 p.m. local time, B.C.’s Joint Rescue Coordination Centre said.

The BC Coroners Service confirmed late Sunday that five people are dead.

The JRCC said the search for survivors had been called off overnight, with 21 rescued and one person still missing.

CTV has learned the tour boat belongs to Jamie’s Whaling Station and Adventure Centres, a company that offers whale watching tours out of Tofino.

The company operates several types of boats, including zodiac-style rigid-hulled inflatable boats and larger 65-foot cruisers, according to its website.

Local residents are helping in "any way they can," following the incident, Tofino Mayor Josie Osborne told CTV’s News Channel. She added that a similar tragedy with a whale watching boat happened nearly two decades ago.

"It does happen in a coastal community," Osborne said. "It’s a beautiful, stunning environment but not without its risks."

Chris McLellan, who lives nearby, told News Channel that he saw more than a dozen emergency vehicles attend the scene following the capsizing.

"The ambulances -- it was just like one after another after another," McLelllan said. "They didn’t stop."

He added that local First Nations people and other whale watching tour boats were the first to respond to the mayday call.

"Everyone just converged when they heard on the radio what was happening," said McLellan, who heard the reports over transmission radio.

The emergency coordinator for the Ahousaht First Nation said four boats from the community helped in the rescue effort.

"In all my years in responding, I’ve never heard about a boat that big being flipped over," Alec Dick told CTV News Vancouver.

Investigators from the Transportation Safety Board of Canada are being deployed to investigate the sinking of vessel, which the agency identified as Leviathan II.

This isn't the first capsizing incident on the whale watching company's record.

In 1998 one of their vessels capsized during an excursion, sending all four people on board into the water. The operator and one of the passengers died.

With files from CTV Vancouver and The Canadian Press