The break-in in the 9600 block of Black Mountain Road was reported about 9:30 a.m., according to San Diego police.
Patrol personnel arrived to find computer cables cut and monitor screens smashed, SDPD public-affairs Officer Matt Tortorella said. It was not immediately clear if anything had been stolen.
A representative of the office told police the crime had occurred sometime after 9 p.m. Tuesday.
Detectives remained at the scene late this morning, Tortorella said.
DeMaio, a Republican, is running to unseat Rep. Scott Peters, D-San Diego, in California’s 52nd Congressional District.