Production also was halted in Los Angeles for the rest of the week.
REUTERS/Aude GuerrucciThe writers are seeking changes in pay and the formulas used to compensate writers when their work is streamed, among other proposals.
The last WGA strike in 2007 and 2008 lasted 100 days.
Writers say changes from the streaming TV boom have made it difficult for many to earn a living in expensive cities such as New York and Los Angeles.
Half of TV series writers now work at minimum salary levels, compared with a third in the 2013-14 season, according to WGA statistics.