Police warned jumpy residents in this city of 8,300 people to be on the lookout for a dangerous suspect who may be someone they know.

Nobody was injured in either fire, the latest of which started shortly after 4 a.m. in the prosecutor's office in a one-story brick building that houses several other law offices in Lancaster's small downtown, authorities said.

Police Capt. Harlean Howard said witnesses to the fires have been interviewed but urged more to come forward. She also said experience shows the suspect will likely follow the investigation closely in media reports and in conversations.