GRESHAM, Ore. -- A fire and explosion damaged eight units, completely destroying four of them, at the Aldercrest Apartment Complex in Gresham Thursday morning.

Firefighters responded to the alarm at 8:11 a.m.

The weather made driving difficult, said Division Chief Todd Keathley. With their fire engine’s tires wrapped in chains, it took crews nearly ten minutes to get to the scene.

When they arrived, they found a hydrant was frozen.

“The crews used road flares and were able to get the hydrant to flow water, so then we were able to reestablish our water supply and go back to work there,” said Keathley.

In the meantime, Keathley said crews used water reserves carried on their trucks, so the frozen hydrant causes little to no delay.

All of the apartments were occupied when the fire started, but Keathley said everyone got out with minor injuries.

Most suffered from smoke inhalation or minor burns. No one had to be transported to the hospital.

He added the apartments were empty when the explosion happened. Firefighters believe flames reached an oxygen tank used by one of the residents.

About a dozen people were displaced by the fire. The Red Cross is working on getting them shelter.

Investigators have not yet determined how the fire started.

KGW viewer submitted photo ( of Gresham apartment fire, Jan. 12, 2017