Investigators are chipping through layers of ice, looking for the cause of Thursday’s fire that gutted two businesses in downtown Hampton and damaged several others. A-Plus Tax Accounting and the Americana Antique Mall were destroyed. The cause of the fire is unknown and investigators are having to deal with a three-inch coating of ice. Hampton fire chief Jeff Ferris says the early-morning blaze was a tough one to fight. Temperatures were so cold, the spraying water was freezing before it could get to the building. Ferris says the damage was kept mostly to the two businesses and the facade was saved — but for naught.The buildings are so weak, the entire front may topple and they’ll likely have to be pushed in. The granite-front buildings were built in the 1890s and were part of Hampton’s downtown historic district.