What began with questions about bulk sales of an obscure children’s book series erupted on Thursday into a full-blown political scandal in Baltimore, where federal agents raided City Hall and two houses belonging to Mayor Catherine Pugh, the author of the books. Critics of the mayor renewed calls for her to resign.

Local news stations aired images of agents from the F.B.I. and the Internal Revenue Service carrying out box after box of documents and other items seized from at least six locations, including Mayor Pugh’s second-floor office in City Hall and her two homes in northwestern Baltimore. The coordinated raids sought financial records related to the children’s books.

Hours later, Gov. Larry Hogan of Maryland, a Republican, called for the mayor, a Democrat, to resign, saying she could no longer govern effectively. “Mayor Pugh has lost the public trust,” Governor Hogan said in a statement. “She is clearly not fit to lead.”

The governor’s demand for Mayor Pugh’s resignation comes a little more than two weeks after the Baltimore City Council urged Ms. Pugh to step down, and three weeks after Governor Hogan ordered a state investigation into the business relationship between Ms. Pugh and a health care system with extensive financial ties to the city.