Six real estate firms indicted earlier this month on federal charges of price fixing were sued yesterday by the Maryland attorney general's office, which seeks to refund nearly $700,000 in real estate commissions collected by the firms from Montgomery County home sellers.

The indicted firms are charged with conspiring in about September, 1974 to raise their commissions from 6 per cent to 7 per cent on sales in the suburban Washington county. The commission charged by most real estate brokers in the area is 6 per cent.

The state action was filed in U.S. District Court in Baltimore under a "parens patriae" law in which the state may act as a "parent" in behalf of its residents.

Tom Wilson, chief of the antitrust division of the attorney general's office, said the state will seek treble damages, about $2 million, from the indicted firms and three of their presidents.

Named defendants in the action yesterday were the same firms and persons indicted by a federal grand jury on April 1: Bogley, Inc., and its president, Robert W. Lebling; Coluiqtt-Carruthers, Inc., and its president, John T. Carruthers Jr.; Jack Foley Realty, Inc., and its president, John P. Foley Jr.; Robert Gruen, Inc., Shick & Pepe Realty, Inc., and Shannon & Luchs Co.