Deadly virus thriller Contagion caught on with filmgoers and easily took the top spot at the weekend box office in the United States and Canada, according to studio estimates compiled by Reuters on Sunday.

Contagion brought in $23.1 million in ticket sales over its first three days of release, distributor Warner Bros. said. The film tells the story of the race to contain a lethal virus that is quickly circling the globe.

The Help, a surprise summer hit about black maids in civil rights-era Mississippi, slipped to second place after three straight weeks at No. 1. The film rung up $8.7 million over the weekend.

Warrior, a new drama about two brothers who battle in a mixed martial arts tournament, pulled in $5.6 million to finish in third place.

Warner Bros., a unit of Time Warner Inc (TWX.N), released Contagion. Lions Gate Entertainment (LGF.N) distributed Warrior. The Help was produced by DreamWorks and distributed by Walt Disney Co. (DIS.N)