No one was injured yesterday after firefighters evacuated a Santa Cruz bank. Officials say the incident started at 11 a.m. at the Bank of America on River Street after a mechanical problem on the building’s roof caused smoke to be sent inside the bank. Both customers and employees waited outside until about 11:30 when the building was reopened. Firefighters found a burned out belt on a heating, ventilation and air-conditioning unit on the roof. No fire was reported.