The crew members were in the Carthage Street station about 1.40am when the "low act" took place, Fire and Rescue NSW Acting Inspector Glenn Willsallen said.

"One of the guys heard the disturbance and ran outside and found a couple of guys jumping over the back fence, running away," he told the Leader.

"They found various personal items from the firefighters' own vehicles had been taken."

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"It's just not right. These were on-duty firefighters, going about their work, and it's changed the whole dynamic of the station," Acting Inspector Willsallen said.

"Because of this, security will need to be ramped up at the station, and we have started that process this morning.

"We have always tried to be an open resource to the community, so that people can come in and look at the fire trucks and talk to our staff about fire safety.

"Now we need to rethink that and ramp up security, and start locking all the doors to the station because of the thoughtlessness and carelessness of two individuals overnight."

The crew rostered on was the same that extinguished the fatal house fire in October in Hillvue.

They have also been battling out-of-control fires, defending homes and backing the RFS since August this year, on top of their usual emergency call-out workload.

The Tamworth firefighters have been deployed on several missions in the past three months, tackling blazes in the Tenterfield and Glen Innes areas, Ebor, Mount Kaputar and Moonbi.

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