Verizon has restored service to approximately 7,000 customers in Lawrence who were affected by a fire that destroyed cables, the utility said Wednesday. The fire occurred Monday morning under the Central Bridge on North Canal Street. Verizon crews have worked at the site since that time, splicing new cables, the company said. About 1,000 customers who live or work in the Lawrence and North Andover area remained without service and Verizon expects them to be restored within a few days, the company said in a statement late Wednesday.