A father and son have been identified as the two people who died in last week's explosion in Nipawin.

Jack Boxall, who was in his 70s, and his son Brent, who was in his early 50s, died following the natural gas explosion Friday morning in the business section of the town, the RCMP said.

On the weekend, investigators were busy going through the rubble, trying to figure out why a gas line was damaged and then exploded.

Officials said they believe construction workers were busy digging on two vacant lots when a backhoe snagged a gas "riser" — a vertical pipe that connects to a meter — pulling it from the main.

Gas started to spread through the soil in all directions, collecting under a local business, BJ's Sausage and Meats.

SaskEnergy workers were able to warn the owner, who was able to get out minutes before the explosion hit.

Saskatchewan fire commissioner Dwayne McKay said many things could have caused the spark that ignited the blast. A water heater pilot light is one example of an open flame that could ignite it, he said. 

Three people were injured in the blast, which caused a fire that damaged other buildings in the town of about 4,000. One has been discharged from Nipawin's hospital, one was transferred to Prince Albert and another was taken to Saskatoon.

The blast blew out windows and sprayed bricks and other debris for more than a block around.

"We saw a building that looked like an orange that had been peeled and spread out," fire investigator J.D. Lloyd said. "The walls had been spread out into the street, into the alley."

It's a miracle more people weren't hurt, Lloyd said.

"This is a remarkable incident in that even though we've had two deaths, the number of injuries and fatalities wasn't far greater, given the time of day, given the location," he said. "It really is miraculous more people weren't hurt."

A gym near the meat store was one of the buildings damaged. One woman was inside a tanning bed when the roof collapsed. She escaped without injury.

Premier Brad Wall has expressed condolences to the family and friends of the victims and said the province will do everything it can to help Nipawin recover from the disaster.

"Every possible resource will continue to be made available as the town rebuilds," Wall said in a news release.

The mayor of Nipawin declared a state of emergency, but that was lifted later on the weekend. People who had been evacuated from a two-block radius around the blast site were allowed to return to their homes.

Gas, power and phone service was down for some residents, but by Monday, everything was back up.

The RCMP said it is continuing to investigate the incident.