A holiday at a resort in Mexico has turned into a nightmare for hundreds of people, including a local family who has relatives staying at the hotel.

The blast happened shortly after 9:30 a.m. local time at the 676-room Grand Princess Riviera Hotel in Playa del Carmen, Mexico, Sunday morning

Officials say the explosion was caused by a ruptured natural gas line under the lobby's floor.

Sherwood Park resident Gene Hoffman tells CTV News his relatives were at the resort for a family wedding. He says he received an email Sunday morning telling him there was an emergency. His sister had been injured in the blast.

"The place was leveled and he said he seen a guy buried up to his neck in rubble," said Hoffman. "[He] couldn't see her anywhere and he came out and he found her on the grass."

Hoffman says his sister Darlene, who's in her early 50s, was rushed to hospital with a collapsed lung and severe internal injuries. She had to undergo emergency surgery, but succumbed to her injuries and died.

Hoffman's family is in Mexico for his nephew's wedding. He couldn't make the trip because he couldn't get time off of work. Seven family members are from Ardrossan and 13 are from Sherwood Park. Many of them are still in shock.

"It was like panic," said Hoffman. "He said there is not a lot of security in that place, people kind of running everywhere; no one really knew what was going on."

Some of the family members were supposed to fly out today but will probably miss their flights. They are not allowed in their hotel rooms, where their passports are.

Five Canadians, including a nine-year-old boy, a 51-year-old man and two other men between 25 and 30 years old were killed in the blast. The death toll stands at seven people.

More than 60 Canadians are staying at the resort.

Anyone seeking information about Canadians who may have been staying at the Grand Riviera Princess Hotel can call the Department of Foreign Affairs at 1-800-387-3124.

WestJet has also set up a "Family and Friends" hotline you can call at 1-866-786-6311.

Playa del Carmen is about 70 kilometres south of Cancun.

With files from Sonia Sunger, The Associated Press and The Canadian Press