More than 6,200 customers of Central Maine Power in Lewiston are in the dark Thursday, according to CMP officials. As of 1 p.m., 6,216 customers had lost power, according to the utility. There are 18,255 CMP customers in Lewiston. “A squirrel got into one of our substations and caused some problems for himself and about 6,200 people in the Lewiston area,” said Gail Rice, a Central Maine Power Co.