LOS ANGELES (Reuters) - The teen horror movie "Prom Night" was the belle of the ball at the weekend box office in North America, earning an estimated $22 million during its first three days, distributor Sony Pictures said on Sunday.

The studio had hoped the defanged remake of a 1980 thriller starring Jamie Lee Curtis would open in the mid- to high-teen millions. It cost about $20 million to make.

The movie played strongly with its target audience of teenagers and was released to coincide with the upcoming prom season -- when presumably teens won't have to run from homicidal teachers who have escaped from mental asylums.

Brittany Snow stars as an orphaned high school student pursued by an obsessed teacher (Johnathon Schaech). It was produced by Screen Gems, the low-budget division of Sony Corp-owned Sony Pictures, which split the cost with Walt Disney Co's Miramax Films.

Also new was the violent cop thriller "Street Kings," starring Keanu Reeves, at No. 2 with a solid $12 million, and the dark family comedy "Smart People" at No. 7 with a modest $4.2 million.

Rounding out the top five, Sony's gambling drama "21" fell to No. 3 with $11 million, after two weeks at No. 1. Its three-week total stands at $62.3 million.

The Jodie Foster family adventure "Nim's Island" dropped two spots to No. 4 with $9 million, taking its 10-day haul to $25.3 million.

The George Clooney football drama "Leatherheads" also was down two, to No. 5, with $6.2 million. The box office disappointment has scored $21.9 million, also after 10 days.

"Street Kings" and "Nim's Island" were released by 20th Century Fox, a unit of News Corp. "Smart People" was released by Miramax. "Leatherheads" was released by Universal Pictures, a unit of General Electric Co's NBC Universal.