PITTSBURGH (AP) _ The second of four volunteer firefighters accused of torching their firehouse to collect insurance money to build a new social hall pleaded guilty Wednesday.

Thomas Baker, the former assistant fire chief, pleaded guilty to mail fraud and aiding the arson of the 15-man department in Isabella, about 35 miles south of Pittsburgh.

Baker's plea came a day after former department vice president Jerry Booker II pleaded guilty to mail fraud and a federal arson charge for a pair of fires authorities said he set in June 2002.

Federal authorities said Baker told Booker to set the fires hoping the department could collect $500,000 in insurance money to build a new social hall. The second fire was set because insurance investigators wouldn't declare the building a total loss after the first fire, authorities said.

Two other volunteer firefighters _ former chief Steven M. Dugan and former trustee William A. Robison _ are awaiting trial later this month on charges they helped file a false insurance claim.