Officials with Occupational Health and Safety confirmed Friday that one man has died after an explosion in a Fort Saskatchewan home Thursday afternoon.

Emergency crews were called to the home on Allard Way, which was under construction in a new development in Fort Saskatchewan, just after 1:15 p.m. Thursday after the explosion was reported.

“It was a flash fire, and then the gas burned out and that was it,” Bob, a witness who had been installing siding on a nearby home when the blast happened, said.

Other nearby workers moved quickly, grabbing one of Bob’s ladders and rushed to reach the men who had been working in the basement of the home.

“Whoever did that they didn’t even think about themselves, they just ran down there,” Bob said.

He said they were suffering from serious burns.

“The one guy was crying out, I don’t know which one,” Bob said.

“’The hospital’s just over there,’ somebody said ‘Why don’t we just drive them to the hospital?’ How do we deal with that? You feel helpless.”

All three men were rushed to hospital – CTV News later learned the three are plumbers, and were working in the basement of the home at the time.

OHS said a 33-year-old man passed away Friday morning from injuries he suffered in the explosion; the other two injured men remain in hospital in critical condition.

Two of the men were identified as brothers, 48-year-old Wes and 42-year-old Wilfred Michalycia, the third was identified as their cousin Jason Michalycia.

According to family members on Facebook, Jason passed away.

CTV News spoke to the father of Wes and Wilfred, who said his nephew was from Saskatchewan.

Occupational Health and Safety has taken over the investigation – fire investigators said late Thursday that the explosion and subsequent fire was caused by a gas leak.

However, an OHS spokesperson said it's too early to say exactly what caused the explosion, all that's known is it was caused by some kind of gas.

With files from Susan Amerongen