An extensive cleanup is underway at a BC Hydro substation near Chilliwack, east of Vancouver, after a fire engulfed the structure Friday.

About 38,000 residents in the area were left without power on Friday after a fire broke out at the Atchelitz substation, located on farm land just west of Chilliwack near the intersection of Lickman Road and South Sumas Road.

Area resident Lawrence Spranger was in his kitchen when the fire broke out.

"We heard a bang ... and we see the smoke and the flames and my wife phoned 911 right away ... We see the smoke billowing and getting bigger and then after 25 minutes, another big bang."

Spranger said thick black smoke could be seen billowing over neighbouring houses.

On Saturday morning work crews had erected a small tent near the site of the fire, but weather hampered cleanup efforts as the area was hit with snow, rain and hail.

'Safety is our top priority'

"This weekend, the focus is on two things. One is making sure the containment is maintained and strengthened. And two is cleaning up," said BC Hydro spokesperson Chris Brumwell.

"We've got a full team out there right now. You'll see trucks, you'll see some tents and you'll see some vacuum trucks out there working away. We'll have a full team there until midnight [Saturday] and then teams on the ground 24 hours a day for the next little while."

Crews will vacuum up the accumulated water and oil, which will then be shipped to a facility and separated so officials can get some idea of how much oil spilled.

"We're working with all the authorities — the environmental authorities, the health authorities — and we have a full team out there right now," Brumwell said. "Safety is our top priority."

The official cause of the fire has not been determined, but unconfirmed reports suggest leaking fuel caught fire.

"As we get into next week, our team will be able to get closer to the actual accident and take a look at how things unfolded and get a better idea of what led to the accident," Brumwell said. "So next week will really be focused into the investigation of what happened."

The Atchelitz substation serves approximately 50,000 customers.