A critically acclaimed science fiction thriller featuring unknown actors and a first-time director invaded theaters this weekend, stealing the number one slot at the box office. "District 9" generated a healthy $37 million on its first weekend out, boosting it light years ahead of the second-place heavyweight "GI Joe: The Rise of Cobra", according to estimates from studio trackers Nielsen EDI and IMDB.com.

"District 9" is an alien invasion film cut from the cloth of 1988’s "Alien Nation" (starring James Caan and Many Patankin), and is produced by Peter Jackson ("The Lord of the Rings" trilogy) and directed Neill Blomkamp, a newcomer to the national scene. The film deals with broad issues of prejudice, apartheid and humanity as gnarly looking aliens seek refuge on planet earth, and it has been one of the best-reviewed movies of the year.

Meanwhile, "G.I. Joe: The Rise of Cobra" was second with $22.5 million, a drop of 59 percent from its debut last week. The film has done $98.8 million in 10 days. "The Time Traveler's Wife" was No. 3 with $19.2 million, while Meryl Streep's comedy "Julie & Julia" cooked up $12.4 million in its second weekend, scoring a 10-day take of $43.7 million. The 3-D comedy "G-Force" was fifth with $6.91 million, bringing its month-long total to an even $99 million.

Final figures are due Monday.

Chart Source: IMDB.com.