The dystopic science fiction thriller "Elysium" topped the weekend box office with $30.5 million, according to studio estimates Sunday, enough to beat three newcomers, including the Jennifer Aniston comedy "We're the Millers."

Sony's "Elysium," directed by Neill Blomkamp and starring Matt Damon, matched expectations, but still opened somewhat modestly for a $115 million action film. It couldn't match Blomkamp's previous film, the $30 million "District 9," which opened with $37.4 million in August 2009.

In second was Warner Bros. R-rated comedy "We're the Millers." It took in $26.6 million over the weekend, and $38 million since opening Tuesday night.

Disney's "Cars" spinoff "Planes" opened with $22.5 million. Fox's "Percy Jackson: Sea of Monsters," a sequel based on young adult novels, came in forth with a $14.6 million opening.