People were ordered to evacuate buildings within a two-block radius of Friday's blast. ((Courtesy of Bryan Young) )

People forced to evacuate their homes and businesses in a small Saskatchewan town after a massive natural gas explosion that killed two people got the green light to return Saturday afternoon.

Sask Energy, the province's publicly owned gas utility, said repairs to a main gas line in downtown Nipawin have been made and crews have reached 302 customers who had service knocked out.

SaskTel said it still has not restored phone service to all customers, but it's expected to be done by Sunday morning.

An evacuation order was issued for a two-block radius after Friday's explosion.

No further details have been released on the two people who died or the conditions of three others hurt in the blast, although one person originally taken to hospital has been discharged.

The explosion destroyed or heavily damaged at least three buildings in downtown Nipawin, about 250 kilometres northeast of Saskatoon.

Reports have said that the two people who died were a father and son who were hauling gravel away from the area and that one was pronounced dead upon arrival at hospital. The second person died in the intensive care unit about 11:30 p.m. local time Friday.

There has been speculation that workers using heavy equipment in the area cut into a natural gas line, but officials on the weekend said the investigation into the cause of the explosion could take several days or perhaps weeks.

A local Sask Energy worker said that on Monday, he noticed a gas line protruding from the ground in a vacant lot where the explosion occurred. He said he clearly marked the pipe by erecting 1.2-metre stakes around it.

J.D. Lloyd of the Saskatchewan Fire Commissioner's Office said investigators have confirmed it was a gas explosion, but they still have a lot of work to do.

"Sometimes, it's likened to archeology in a way. We'll be very carefully going through the scene and gathering information and evidence that we hope will lead us to determining the cause of this particular explosion," he said.

With files from the Canadian Press