A suspected natural gas explosion tore through the lobby of a Mexican resort Sunday, killing seven people. Five Canadians were among the dead, including a nine-year-old boy.

Another eight Canadians were injured in the blast, and two are in critical condition.

The explosion occurred shortly after 9:30 a.m. local time at the 676-room Grand Riviera Princess Hotel in Playa del Carmen, which lies on the Yucatan peninsula south of Cancun.

Along with the nine-year-old child, a 51-year-old man and two men between the ages of 25 and 30 were among the Canadians killed at the hotel, according to Jesus Puc, the director of the civil protection agency. Two Mexicans also died.

Edmonton resident Gene Hoffman told CTV News Channel that he had more than 20 relatives at the resort, including his brother and sister.

After the blast, his brother found his sister "bleeding on the sidewalk" and she was transported to Cancun for medical treatment.

"She has a collapsed lung, severe internal injuries, a few broken ribs and severe lacerations to her face," Hoffman said.

His sister's grandson, who is two years old, was also hurt in the explosion and is being treated at another hospital in Cancun.

Francisco Alor, attorney general for the state of Quintana Roo, said that investigators were examining whether a build-up of natural gas from a swamp near the hotel may have led to the explosion.

At least 60 Canadian tourists from Ontario's Kitchener-Waterloo region were staying at the hotel, while reports say other guests were from Alberta, Winnipeg and Quebec. WestJet spokesperson Richard Bartrem said more than 400 Canadians had booked vacations at the resort through his company.

Ray Hamblin from Toronto was in the adjacent restaurant when the blast occurred.

"Everybody was enjoying their breakfast and basically there was a loud explosion," Hamblin told CTV News Channel in a telephone interview from Mexico Sunday afternoon. "It sounded like lightning struck right beside you."

The blast blew out 12-foot glass windows separating the lobby from the restaurant, Hamblin said.

Freelance journalist Ioan Gillo said between 15 and 20 people were taken to hospitals in the area.

In a video of the aftermath posted on YouTube, part of a roof around one of the resort's buildings has collapsed, and glass and debris are scattered along common areas. Victims can also be seen being loaded onto ambulances that line a driveway.

Mark Bingeman said he witnessed people being pulled out of the debris, covered in cement dust.

"There didn't appear to be any structural damage" to the building, he said. "But certainly everything was just devastated inside."

The explosion left a four-foot deep crater in the ground, according to guest James Gaade, who estimated that at least half of the guests at the resort were Canadian.

Staff at the hotel have evacuated the main building and an adjoining building, and have cleared the lawn in front the explosion site. Guests were being relocated to rooms in other areas of the resort.

A spokesperson for the Department of Foreign Affairs said officials are monitoring reports of the explosion.

Lisa Monette told The Canadian Press that the consulate in Playa del Carmen is prepared to provide consular assistance to any Canadians staying at the hotel.

"We are aware that a number of Canadians are at the Grand Riviera Princess and are endeavouring to determine if any have been affected," Monette said.

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

With files from The Associated Press and The Canadian Press