‘The Walking Dead’: Graphic opening even shook up producers

“The Walking Dead” has always had more than its share of over-the-top violent moments. But the start of Sunday’s fifth season curtain-raiser was so gut-wrenching that even some of the show’s key creative forces were shaken.

(SPOILER ALERT: VIEWERS WHO HAVE NOT YET WATCHED SUNDAY’S EPISODE OF “THE WALKING DEAD” SHOULD STOP READING NOW).

In the opening moments, Sheriff Rick Grimes (Andrew Lincoln), several of his male comrades and other prisoners at the Terminus outpost were bound, gagged and forced to kneel in a line in front of a trough inside a huge warehouse.

Then one of the captors viciously swung a bat into the head of one of the unfortunate prisoners, knocking him out. Another captor then took a massive blade and slashed the throat of the unconscious man, causing his blood to pour into the trough.

The attackers moved down the line, killing two other men in the same ferocious manner as they moved closer to killing Rick and his companions.

Even given the extreme violence and gore of “The Walking Dead,” the sight and sound of the captives being slaughtered was particularly horrific. Executive producer and show runner Scott M. Gimple noted the heart-pounding opening during his remarks at last week’s gala premiere of the series at Universal Studios.

The sequence marks another entry in the escalating trend of brutal, explicit violence in some of television’s elite dramas.

Prominent in the category is one of the landmark episodes of “Breaking Bad” in which drug kingpin Gus Fring (Giancarlo Espositio) donned plastic overalls before tearing open the throat of one of his underlings with a box cutter.

In the current season of “Boardwalk Empire,” mobster Al Capone (Stephan Graham) bashed in the head of one of his accomplices with a small statue. In previous seasons, a man was scalped, and another victim had his throat slashed while hanging upside down in a butcher shop. FX’s “Sons of Anarchy” regularly centers on brutality, with explicit scenes of shootings, stabbings, maiming and torture.

What did you think of the opening of “The Walking Dead”?