The structure fire was reported at 10:58 p.m. Thursday, July 4 at 4021 Park Ave., according to the Fairfield Fire Department.
A sleeping resident was awakened by the sound of the fire and alerted her family and called 911, said the department.
Multiple vehicles responded to the fire behind the five-unit condo complex and put out the fire.
"Had the resident not been awakened, this fire would have grown rapidly and the outcome could have had a very tragic ending," said Fairfield Fire Department Public Information Officer Lt. Robert Smith.
The blaze was caused by illegal fireworks shot off in the immediate area, according to the department.
"The Fairfield Fire Department would like to remind everyone about the dangers of using illegal fireworks and will continue to strictly enforce the State Statute for all those found in violation," said Smith.
Police are investigating the fire.
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