Los Angeles ? As TV and film writers and their employers dig in for a potentially long strike, production is grinding to a halt.

Writers were in their third day of pickets Wednesday as they strike over residual payments for work distributed over the Internet and other issues.

Several multi-camera sitcoms, whose writers tend to be on set every day, have already gone dark, among them CBS’ “The Big Bang Theory” and “Two and a Half Men” and Fox’s “‘Til Death,” according to various reports. Another Fox show, “Back to You,” was supposed to come back from a planned hiatus on Wednesday, but instead will stay closed.

Elsewhere, “How I Met Your Mother” is shooting this week, as are a number of single-camera shows, including NBC’s “My Name Is Earl” and “Scrubs” and ABC’s “Carpoolers,” which is finishing its 13-episode order this week. Work on NBC’s “The Office,” however, has been disrupted as several cast members, including Steve Carell, B.J. Novak and Mindy Kaling – all of whom have also written episodes of the show – walked the picket lines.

No new talks between the Writers Guild and the Alliance of Motion Picture and Television Producers have been scheduled.