The fire started around 1 a.m. Tuesday inside a row of stores at the Green Hill Plaza on Parsippany Road.
One firefighter was taken to Morristown Medical Center and is in stable condition. No other injuries were reported.
Parsippany Road was closed between Barnsboro and Allentown roads due to the firefighting efforts.
Smoke was still billowing from the scene after 6 a.m.
The cause of the fire is under investigation.
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