The radio network used by fire crews during Sunday's devastating Parkerville blaze was hacked during vital stages of the response, forcing firefighters to abandon the channel for a less effective one.
Volunteer crews say lives and property were put at risk by the "totally irresponsible" behaviour of one or more people transmitting on the WA Emergency Services radio network.
The frequencies are used by emergency services including the Department of Fire and Emergency Services, Volunteer Bushfire Services and the Department of Parks and Wildlife.
Mundaring deputy chief bushfire control officer Rod Eyre was a sector commander during Sunday's fire and said the interference was dangerous and frustrating.
"Our effect was being seriously impinged by a totally irresponsible person up to mischief," Mr Eyre said. "We had to lose an effective radio channel and go to a lesser radio channel to overcome the interference . . . There's the possibility of an element of attribution of loss to that person."
The Department of Premier and Cabinet confirmed its email server shut down for "a few hours" on Sunday and Monday while the fires raged after it was inundated with anti-shark cull emails stemming from a Greenpeace campaign.
A spokesman said the influx "did have an adverse impact on the department's ability to communicate during the recent bushfires with the potential to affect its role in assisting DFES and other agencies in the response to those fires".
Mr Eyre hopes the culprits behind the radio interference will be caught and prosecuted.
Mundaring Volunteer Bushfire Brigade volunteer Ricky Harvey, who fought the ferocious blaze alongside Mr Eyre and hundreds of other firefighters, said the interfering transmission was "crystal clear". "It was random chit-chat and generally annoying chatter which quite literally was hampering the firefighting efforts," he said.
"It may sound like a cliche but they were quite literally putting lives at risk, it was amazingly frustrating on the fireground."
Both men said the voices sounded juvenile and they continued for about an hour despite fire crews urging them to get off the channel.
It is not known how those responsible got access to the radio channel but the Australian Communications and Media Authority said it would investigate any reports of interference, which could result in prosecution under the Radiocommunications Act.
"The ACMA takes the matter of intentional interference with regards to public safety very seriously," a spokeswoman said.
"There is a range of compliance and enforcement actions open to the ACMA for breaching the act including criminal prosecution.
"The ACMA can also seek approval from a court for the issue of a search warrant authorising the search of premises and the seizure of radio communications equipment that would afford evidence of the offence."
The spokeswoman said the behaviour was contrary to four sections of the Act, and fines up to $850,000 applied to anyone found guilty of interference with radio communications likely to endanger safety or cause loss or damage.
The maximum penalty for unlicensed operation of radio communications is two years jail.
A DFES spokeswoman said reports of interference would be addressed in a post-incident analysis of the fire, which was sparked by a privately owned power pole and destroyed 56 homes.
Mr Eyre and Mr Harvey paid tribute to fellow volunteers.
Dave Gossage, from the Association of Volunteer Bush Fire Brigades, said he had the "utmost admiration" for those who fought the terrifying blaze. "They understand what needs to be done and they get out and do it, for as long as they can," he said.