The lights went out Friday in about 1,800 Anne Arundel County homes and businesses, as thieves snipped copper wire from a utility pole, authorities said.

About 250 feet of wire was taken from a Baltimore Gas and Electric pole in the 1000 block of Annapolis Road in Odenton, the county police said. Police received a report of suspicious activity and showed up shortly after midnight. A vehicle was stopped, tools were seized and four people were arrested, the police said.

The day before, Metro transit police said they arrested a man who took copper wire “on multiple occasions since June” from sites that included the Greenbelt Rail Yard. The copper was then sold, Metro said.

Copper theft, which is thought to be prompted by the more than $3 price of spot copper, has been increasing in parts of Montgomery County, the police there said Wednesday.

“Vacant homes, especially homes for sale, have been most commonly targeted,” the Montgomery police said. Thefts have been on the rise in the Silver Spring area in particular but were occurring elsewhere as well, county police said.

In the District, a neighborhood watch trainer recently posted an e-mail saying that “the copper downspout thieves are out there and active again.”