The offenders are alleged to have entered the premises in a silver Holden Commodore with stolen number plates.
After gaining entry to the car park, they allegedly broke into five vehicles, including an unmarked police car.
The group then fled the scene in an allegedly stolen black BMW and the commodore they arrived in, allegedly taking off with a police issued firearm and ammunition.
At least four men have been arrested in raids carried out across Townsville, according to police.
Those taken into custody include; a 40-year-old man, a 24-year-old man and a 25-year-old man.
They were charged with various stealing, drug and weapon possession offences.
A fourth man, aged 18, was allegedly involved in a separate armed robbery at a home on Douglas Street later on Sunday.
He was charged with enter premises and commit, enter premises with intent to commit, unlawful possession of weapons and unlawful use of a motor vehicle.
All four men are due to appear before Townsville Magistrates Court today.
Police said investigations are continuing to locate the missing gun and ammunition.
Anyone with information is urged to contact police.