The fire is visible from I-95 and is slowing traffic in that area, the Connecticut Department of Transportation said.
Route 130, or Stratford Avenue, is closed in both directions between Kossuth and Water streets, DOT said.
Scanner reports said the blaze is in an empty factory near Water Street.
At least two engine companies and the Bridgeport Fire Department's fireboat have responded to the scene, according to scanner reports.
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