Several agencies from Hunterdon and Mercer counties responded to the blaze on Pleasant Valley Harbourton Road just before 7 a.m.
Heavy flames ignited the two-story garage, which quickly went to a second-alarm fire due to water supply issues, Raritan Township Fire Company said.
The fire was knocked down and placed under control after a few hours.
The cause wasn't immediately known as of Wednesday afternoon and the incident remained under investigation.
Photos by the Raritan Township Fire Company.
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