Eighteen firefighters were called to Kingsley Road in Fredericton after explosions were heard coming from a two-storey garage on Friday night.
Fire Platoon Captain Steve Fraser said the fire started at around 6:15 p.m.
The garage was a private building used for work on heavy equipment.
Fraser said the explosions were caused by Oxy Acetylene tanks, often used for welding, and other chemicals used for farming.
Crews said the area had to cool down slowly because some metal power tools stored in the garage kept sparking when they were hosed down.
No one was hurt and crews were able to keep the blaze from damaging a nearby house.
There is no word on what started the fire.