Demitra set up both of Gaborik's goals and scored on an assist from Gaborik. The pair has combined for 66 points in Minnesota's last 24 games. The Wild moved back to within one point of idle Vancouver for the lead in the Northwest Division.
It was the fifth loss in six games for the Blues, who are 10th in the Western Conference.
Outshot 12-5 in the opening period, the Blues still emerged with a lead after Doug Weight converted a 2-on-1 break, snapping a hard wrist shot past goaltender Niklas Backstrom's glove.
It took Minnesota nearly eight minutes to register its first shot of the second period, but the Wild tied the game shortly thereafter. Demitra, who spent seven-plus seasons with the Blues, scored against his former team for the fourth time this season.
Exactly two minutes later, the Wild took their first lead when a long lead pass from Pierre-Marc Bouchard to Brian Rolston turned around Blues defenceman Eric Brewer. The momentary lapse gave Rolston a clear route to the net, and he scored his team-leading 30th goal with a wrist shot. It was just the fifth goal in 17 games for Rolston, who has slowed down offensively since missing three games in February due to the flu.
Gaborik scored power-play goals late in the second and eight minutes into the third as the Wild won at home for the 25th time this season.
Chris Sanford made 32 saves for the Blues. Backstrom, who has taken over as the Wild's No. 1 goalie with Manny Fernandez out with a sprained left knee for the rest of the regular season, had 22 saves.
Notes: The game's first whistle came in the opening minute when officials noticed an extra puck had been left on the ice during warmups. ... Rolston recorded the fifth 30-goal season in Wild history. He and Gaborik are the only Wild players to have accomplished that feat. ... Blues captain Dallas Drake missed his third consecutive game after injuring his left wrist when he slid into the boards during a loss at Vancouver on March 15.