The strike began in New York just after midnight, The New York Times reported. Plans called for pickets to begin at 9 a.m. EST outside Rockefeller Center in New York.
The walkout began 13 hours after federal mediator Juan Carlos Gonzalez called labor and management representatives together for a meeting in Los Angeles. The meeting was called amid back-channel discussions focusing on possible concessions from labor and management, Daily Variety reported.
The Los Angeles Times reported the WGA sent an e-mail to its members Sunday, reminding them that the guild "will go on strike" Monday at 12:01 a.m.
Variety said key Hollywood players pushing Sunday to avert a strike included producer and former WGA President John Wells, as well as top studio executives Robert Iger (The Walt Disney Co.), Peter Chernin (Fox), Les Moonves (CBS) and Barry Meyer (Warner Bros.)
The WGA and the Alliance of Motion Picture and Television Producers are locked in a dispute on key issues such as writer compensation for work distributed on DVDs, the Internet, mobile phones and other new media.
2014: The Year in Music [PHOTOS]