A commercial building was heavily damaged by a fire on Friday night, authorities said. Durham firefighters were called to the report of a structure fire shortly after 9:30 p.m. on Friday night just off U.S. 70 in east Durham. When firefighters arrived, they reported heavy fire and requested backup. A second alarm was sounded at 9:45 p.m. The fire happened in a series of trailers used as a construction office for the East End Connector highway project.