LOS ANGELES - Demi Lovato recalls with delight "my first - and my only! - fan mob scene."

The 15-year-old had dropped by a friend's autograph session at a Disney Studios event to say hi when suddenly a little girl shrieked her name. Within seconds, hundreds of kids clutching pens and autograph books had surrounded her.

"I was like, 'What! How do you even know me?' " says Lovato, rising partly out of her chair, tossing up her hands in disbelief and bursting into laughter.

"But yeah," the actress adds quietly, regaining her composure. "It was like, 'This is the coolest thing ever.' "

Greater fame ahead?

As the star of the latest Disney Channel original movie,

Camp Rock

- which premieres on June 20 at 8 p.m. and which the Mouse House hopes will be its next

High School Musical

- it's a scene Lovato might have to get used to.

Only time will tell whether the Disney Channel can capture lightning in a bottle twice in the same decade. Disney is clearly banking on it, however, rolling out buzz about the movie on the Internet for months, offering various Camp Rock tchotchkes and casting as costars the mega-hot pop group the Jonas Brothers.

"People are expecting it to be the next High School Musical. That would be an honor if it is," says 14-year-old Alyson Stoner, who plays budding music producer Caitlyn Geller.

In the film, Lovato plays Mitchie Torres, a musical prodigy who can't afford to attend a prestigious music camp filled with snooty rich kids until her mother gets her a break on the tuition by landing them both jobs in the kitchen.

Once there, she's befriended by miscreant rock star Shane Gray, played by 18-year-old Joe Jonas. She's also hounded by the rich girls, particularly after she's outed as a kitchen worker, until one of them (17-year-old Anna Maria Perez de Tagle) comes over to her side.

Then, in the time-honored tradition of kid musicals dating to the days of Mickey Rooney and Judy Garland, they bring everybody together for a show at which the irrepressible Lovato says happily, "I get to rock the house."

As was the case when the first High School Musical film debuted in 2006, most of its teen stars, although unknown to mainstream audiences, already have followings among the demographic of 8- to 13-year-olds.

A cult following

Lovato developed a cult following as one of the stars of

As the Bell Rings

, the five-minute mini-show Disney uses to fill breaks between its regular programming. Stoner, who appeared in both of the

Cheaper by the Dozen

films, voices Phineas' precocious girlfriend in the Disney cartoon series

Phineas and Ferb

. Perez de Tagle, whose grandmother is prominent Philippine singer-actress Sylvia La Torre, plays the tone-deaf singer, Ashley DeWitt, on the Disney series

Hannah Montana

.

The three actresses say they became friends years before their current project, having bumped into one another at auditions and acting classes. The friendships, they say, made filming the movie easier.