Arizona power plant explosion injures 4 firefighters

An explosion at a power plant in Arizona injured four firefighters.

It happened Friday night just outside Phoenix.

The Peoria firefighters were responding to a battery fire at the power substation.

As they were making entry, there was an explosion.

The force of the blast knocked the helmets and facemasks off the firefighters.

One firefighter, who was knocked unconscious, is in critical condition.

Two others are in serious condition.

A fourth firefighter is stable with minor injuries.