An apparent natural gas explosion at the Grand Riviera Princess Hotel in Playa del Carmen, Mexico, killed seven people, including five Canadians, and injured at least 18 others on Sunday. ((Courtesy of Novedades de Quintana Roo))

Five Canadians are among the seven people killed in an apparent natural gas explosion at a resort in Playa del Carmen, authorities say.

Two Mexican workers were also killed in the blast Sunday morning at the 676-room Grand Riviera Princess Hotel in the tourist region known as the Mayan Riviera, said Francisco Alor, attorney general of Quintana Roo state.

Eight other Canadians were injured, including two who are listed in critical condition. Ten other people, including two U.S. citizens and eight Mexican employees of the hotel, suffered less serious injuries and were listed as stable.

Local officials said the Canadian dead are a woman and four males: a nine-year-old boy, a 51-year-old man and two other men between 25 and 30 years of age.

Relatives identified the woman as Darlene Ferguson, 52, from Ardrossan, Alta., east of Edmonton, who was in Mexico for her son's wedding.

She was walking with her grandson to the beach just before breakfast when the explosion happened, according to her brother, Barry Hoffman, whom CBC reached at his office in Sherwood Park. Her grandson was injured and is in hospital.

"It's really sad. The family's really, really shook up," Hoffman said. "We're all in shock. It's something you never expect, this devastating, to the whole family.

"She looked forward to the wedding and the holiday, and they were supposed to be there for another week," he said.

Another of the victims was Malcolm Johnson, a realtor with Coast Realty in Nanaimo, B.C., who travelled to Mexico last week to get married, his friend David Komo said in an interview.

"He got married a couple of days ago. His wife and daughter were down there with him," Komo said, his voice breaking with emotion. "His daughter is one year old."

An emergency worker combs through rubble following a blast in the lobby of the Grand Princess Riviera Hotel that sent chunks of flooring through the roof and left a crater a metre deep inside the building. ((Courtesy of Novedades de Quintana Roo)) Alor described a horrific scene in which the floor of the building was basically hurled through the ceiling by the force of the explosion, blowing out windows and sending fragments of aluminum window and ceiling panels over a wide area.

Mexican authorities said initial investigations were focusing on the possibility that naturally occurring gas from a nearby swamp had built up under the hotel lobby's floor and somehow ignited.

Canadian consular officials were at a hospital where at least some of the injured were taken.

They said Canadian citizens at the resort who need emergency consular assistance should contact the Canadian Consulate in Playa del Carmen, at 52 (984) 803-2411.

They can also call the Department of Foreign Affairs emergency operations centre, collect, at 613-996-8885. An email can be sent to sos@international.gc.ca.

"On behalf of the government and all Canadians, I offer my condolences to the family members and friends of those who lost their lives and wish a quick recovery to those who were injured," Foreign Affairs Minister Lawrence Cannon said in a statement.

"I also extend my sympathies to everyone affected by this terrible explosion."

Hotel rooms shook, windows shattered

Pete Travers, news director of 570 News radio in Kitchener, Ont., is staying at the hotel with a group of Canadians from Waterloo, Ont. He said he heard a loud crash and rushed out of his room to find the glass windows of a hotel restaurant blown out.

Travers said he and a few other guests rushed to grab deck chairs from the pool area to use them as make-shift stretchers for the injured.

"There was blood and injuries from flying glass and debris. No way of knowing just how injured these people were," Travers said. "I saw three or four people receiving triage, they appeared to my eyes to be tourists."

Damage is evident to a part of the Grand Princess Riviera Hotel in Playa del Carmen, Mexico, after an explosion Sunday that killed seven people, including five Canadians. ((Pete Travers/570 News/Canadian Press)) Carson Arthur, 39, said in a phone interview that "all of the air was sucked out of every open door, every room and then pushed back at a huge rate."

"The velocity of the air coming back was incredible, so people were thrown around all over the place in the rooms and hallways," said Arthur, who is on vacation with six friends. "There were several people in the debris, there was a lot of people wounded from flying glass."

Hours after the blast many guests of the hotel were still in a state of shock, Arthur said, "I don't know that it's really set in yet for me, there's been lot of people who can't stop shaking."

James Gaade of St. Catharines, Ont., told The Canadian Press he was walking on the beach when he heard the explosion and saw smoke coming from the platinum lounge, a part of the resort that costs extra.

Hundreds of Canadians were staying at the 676-room Grand Princess Riviera Hotel when an explosion happened around 9:30 a.m. local time Sunday. ((CBC) ) "I looked and you could see that the roof [of the restaurant] had collapsed," he said. "There was a large crater in the area, debris. Everyone said their hotel room shook. The glass at neighbouring restaurants all cracked and blew out. The tiki hut that was in the area, that was on fire."

Gaade estimated that more than 50 per cent of the guests staying at the resort were Canadians and said he had met people from Ontario, Alberta, Winnipeg and Quebec.

Many of the Canadians had booked their holidays with Westjet Vacations.

"Our primary concern is identifying those Westjet Vacation guests that are staying at the hotel and determining their status at this time," Richard Bartrem, vice-president of public relations for Westjet said. "We do have representatives on the ground at the hotel as well as we have activated grief counsellors should anybody actually need any of their services."

Bartrem also said the company is holding a meeting Sunday night with the Canadians to find out how many of them want to interrupt their vacations and return to Canada.

"We're in the process of securing additional aircraft in the event that there are people that are looking to get out early … we will be able to accommodate that," Bartrem said.

Early Monday, WestJet executive Robert Palmer said the airline would send a plane to Mexico to pick up Canadians who want to return home. He said the plane would fly to Calgary, but did not have a timetable.