Hazlet's fire companies have made repeated house calls to the site of Sunday's commercial building fire on Phyllis Street, off Clark Street near Matawan to fight flare-ups.
Police Chief James Broderick said the large building shared by two companies at the end of Phyllis Street was substantially damaged in the initial 11:24 a.m. Sunday fire. He said he was not aware of reported injuries.
"The Fire Marshal determined it was electrical in nature," said Broderick.
Reports of smoke and a flame on the roofline drew firefighters again on Tuesday and Wednesday.
Fire response was by Hazlet's three fire companies and First Aid squad, as well as Rapid Intervention Teams from Matawan and Union Beach.
The building is shared by a construction company and mold remediation company.
The street was also the site of a huge fire about a decade ago, when a plastics company burned down at the corner of Phyllis and Clark Streets.