Lightning struck an apartment building in Waterville on Wednesday night, popping a couple of circuit breakers, but it did not start a fire, according to the Waterville Fire Department.

A swath of central Maine thunderstorms also knocked out power to more than 18,000 Central Maine Power customers as of 6:30 p.m., with more than 5,000 homes and businesses without power in Franklin, Kennebec and Somerset counties. As of 10 p.m., the number of outages had been reduced to about 13,300.

A little after 6 p.m., a thunderous bang sounded in downtown Waterville as lightning struck 5 Silver Place, according to Waterville fire Capt. Rodney Alderman. Firefighters responded but there was no fire, Alderman said. They reset the circuit breakers and turned the building over to its maintenance staff.

Thunder started in the Waterville area a little before 5 p.m., followed by spots of heavy rain and lightning. The National Weather Service issued a flash flood warning until 9:15 p.m. for central Maine.

The majority of outages are in Oxford County, with more than 6,700 in the dark, followed by more than 4,400 in Piscataquis County and about 3,700 in Franklin County. Nearly 1,000 are without power in Somerset County with more than in the dark in Kennebec County.

Southern Maine was experiencing off-and-on heavy rain and thunderstorms throughout Wednesday evening.