The highly anticipated High School Musical 3 movie began shooting on Saturday in Salt Lake City, and E! News got the scoop:

Ashley Tisdale was escorted around the set by a police officer who never left her side, except when cameras were rolling. E! News’ set spy said she looked really sad. She never cracked a smile and did not socialize with anyone, except Vanessa Hudgens, who wasn’t working but showed up late in the afternoon to hang out.

It’s worth noting that Tisdale, who plays the spoiled Sharpay, was done up in a pink cowgirl costume, which might make anyone a bit glum.

Zac Efron, Corbin Bleu, Ryne Sanborn and Chris Warren were also on hand, shooting classroom scenes. Though all the actors had their own well-guarded trailers, the guys tended to hang out on set and chat with extras and crew.

Olesya Rulin wore sunglasses indoors all day. The extras got a kick out of that Hollywood-esque move.

Director Kenny Ortega personally directed the extras and was "extremely gracious to all of us," said our set source. "He was carrying around Ashley's dog all day. He was holding it as if it lived in his arms."

Wait a minute—he had her dog? Maybe that’s why she was so glum.

Check back for more on-set HSM3 scoop as filming continues…