San Francisco, CA -- (Sports Network) - The San Francisco 49ers have reportedly agreed to a four-year contract extension with running back Frank Gore.

The San Francisco Chronicle, citing a league source, said Gore will receive a signing bonus of $6.5 million and will earn nearly $14 million in guaranteed money for the duration of the extension. He had one year remaining on his original three-year contract.

Gore set a franchise record last season with an NFC-best 1,695 rushing yards, topping Garrison Hearst's 1998 mark of 1,570. He added 485 yards receiving for a total of 2,180 yards from scrimmage to eclipse Hearst's previous club record of 2,105 total yards.

The 49ers selected Gore in the third round of the 2005 NFL Draft after a collegiate career at Miami-Florida that included torn ACL injuries to each knee. He led the Niners in rushing during his rookie campaign with 608 yards while playing 14 games.