A fire was set Sunday in a Boston ballot drop box holding more than 120 ballots in what Massachusetts election officials said appears to have been a “deliberate attack,” now under investigation by the FBI. The fire was set around 4 a.m. in a ballot drop box outside the Boston Public Library downtown, Massachusetts Secretary of the Commonwealth William Galvin’s office said. There were 122 ballots inside the box when it was emptied Sunday morning, and 87 of them were still legible and able to be processed, Galvin’s office said.