Assistant head coach and offensive line coach Bill Callahan will take over on an interim basis, a source told ESPN's Adam Schefter.
"Through the first five games of the 2019 season, the team has clearly not performed up to expectations, and we all share in that responsibility," the team wrote in a statement. "Moving forward, we are committed to doing all that we can collectively as an organization to turn things around and give our Redskins fans and alumni a team they can be proud of in 2019 and beyond."
Washington's troubles at quarterback played a key role in Gruden's firing. Veteran Case Keenum started the year under center, but the coach replaced him with rookie signal-caller Dwayne Haskins midway through a Week 4 blowout loss to the New York Giants. Haskins threw three interceptions in the contest.
The Redskins turned to Colt McCoy in Week 5, with similar results.
Gruden admitted he didn't have a plan at quarterback ahead of Washington's matchup with the Patriots and appeared reluctant to start Haskins. The 52-year-old coach reportedly didn't want to draft the Ohio State product at No. 15 overall. He apparently preferred a more experienced passer but was overruled by team owner Daniel Snyder.
Adding to Gruden's troubles, several social media videos surfaced last week showing him smoking an unidentified substance and chatting with a young woman. The Redskins declined to comment on the videos.
Washington named Gruden its head coach in 2014. He amassed a 35-48-1 record with one playoff berth. The former Arena Football League MVP previously served as the Cincinnati Bengals' offensive coordinator from 2011-13.