SAN JOSE — Fire investigators and police detectives are probing whether some or all of two-dozen suspicious car fires reported since mid-December are the work of a serial arsonist, according to the San Jose Fire Department. No one has been injured in the string of blazes, which began Dec. 18 and resumed early Tuesday with a flurry of 11 overnight car fires. The fires cover a 5 square-mile footprint spanning the SAP Center downtown and Willow Glen, and extending east to Almaden Expressway. “This remains an active and ongoing investigation as fire and law enforcement officials work to apprehend those responsible,” the fire department said. Information for investigators can be sent to the SJFD arson tip lin at 408-272-7766.