(CNN) - Four firefighters were injured in an explosion while responding to a call for hazardous materials at an electric company in Arizona on Friday night, authorities said.
An additional four others were transported for evaluation following the blast at the Arizona Public Service Electric Company in Surprise, said Fire Medical Department Battalion Chief Julie Moore.
There's no danger to the public or the environment, Moore told CNN affiliate KPHO/KTVK.
In a statement, a spokesperson from the electric company said they had an equipment failure at their storage facility. The cause of the failure is still under investigation, it said.
The four injured firefighters are from Peoria Fire and were hurt when an explosion hit as they entered the facility, according to Fire Capt. Ken Wier.
The force of the explosion was enough to knock the helmets and face masks off the injured firefighters, he said.
One firefighter is in critical condition after being knocked unconscious in the explosion. Two other firefighters are in serious condition -- one with acid burns to their leg and another one suffering from facial trauma. A fourth firefighter suffered minor injuries, Wier said.
CNN's Andy Rose contributed to this report
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