The Tuggeranong Baptist Church was unable to be saved after the blaze broke out just after 6am, completely engulfing the building.

While the inferno was extinguished by fire crews shortly after 10am, its assistant pastor Paul Massen said nothing was able to be salvaged from the ruins.

"The damage is unbelievable. It can't be repaired obviously and it can't be replaced," he said.

"I couldn't find anything that hadn't been damaged and it's quite a big building. Some of the walls have collapsed and the roof has buckled and caved in.

"I don't think there's any way of salvaging it at all."

A structural engineer had been brought in to assess the site following the blaze.

Such was the intensity of the fire that crews weren't initially able to get inside the building.

The church's assistant pastor said everything was as normal when he was at the church building on Friday afternoon, only for it to be destroyed just a few hours later.

Nearby buildings were able to be saved by fire crews, who helped to prevent the blaze spreading.

Mr Massen said many in the church community were finding it difficult to comprehend that the fire may have been deliberately lit.

"It hasn't sunk in that there's someone in Canberra who would do this," he said.

"...We're thinking of where do we go from here."

As well as the damage to the church building itself, the church's op shop was also destroyed in the fire, along with the recently renovated kitchen which would provide free hot lunches to the community.

"The op shop had been going for seven years and there were probably 1000 items there from clothing to pictures to jewellery and pots and pans," Mr Massen said.

"The op shop provided the finances for the community lunches as well as food vouchers for families doing it tough, and the vouchers would sometimes be assistance with electricity bills."

Despite the damage to the church, which began in the early 1980s, Sunday's regular service is still going ahead on the front lawns at 10am.

"There's also going to be a meeting on Sunday afternoon to talk about a plan on what to do from here," Mr Massen said.

Kambah resident Ben Langley was walking his dog just after 6am when he saw the church was ablaze.

"I live pretty close to the church, and not far after I left I saw the flames and, as I got closer, I could tell it was the church," he said.

"From Drakeford Drive you could see the flames."

Mr Langley said he used to attend the church as a teenager, and said he had "many good memories" of going there every week.

A spokeswoman for ActewAGL confirmed power was shut off in parts of Kambah on Saturday morning to assist firefighting efforts.

Mr Massen said he is more than optimistic the church will continue on in the wake of the fire.

"The Tuggeranong Baptist Church will survive and continue to do the things we've always done."

Police are calling for anyone with information about the fire to contact CrimeStoppers on 1800 333 000.