Schwartz, who has 10 goals, scored once in each period for his fourth career hat trick and first since Oct. 18, 2017, against Chicago.
''It's a nice feeling. Maybe you grip the stick a little bit less when you see a couple going in and see a little bit more of the net,'' he said. ''Obviously, the linemates and the other players made great plays on those goals, and some nights they just seem to find a way and others they don't.''
St. Louis jumped out to a 4-0 lead before the Oilers scored twice late in the second period. The Blues added three goals in the third.
Schwartz opened the scoring at 11:41 of the first. He got the puck in the corner, skated into the left faceoff circle and lifted the puck from a bad angle over goalie Mikko Koskinen's glove.
Perron got an assist after his takeaway in the neutral zone started the play, extending his point streak to 16 games. Perron was playing his third game after missing 24 with an upper-body injury. He has 20 points in those 16 games.
Pietrangelo scored his 13th goal 27 seconds into the second period. From the left side, Schwartz passed to a wide-open Pietrangelo in the slot. He skated in and faked to his right before going left and slipping the puck into the net.
Schwartz scored his second goal at 5:42 to make it 3-0. He fired a wrist shot from the left circle that hit Koskinen's right pad and trickled in.
''I think you need to relax a little bit. You feel more confident with the puck,'' Schwartz said. ''Maybe find open areas a little more. I think in any sport when you're having a little bit more success it gives you a little bit better feeling.''
Perron scored from behind the net at 7:14, making it 4-0.
The Oilers got on the board at 18:28 when Nugent-Hopkins scored from the right side, making it 4-1. It was just the 12th shot on goal for Edmonton.
It appeared Blues rookie goaltender Jordan Binnington made the save, but after a replay review officials ruled the puck crossed the goal line. Nugent-Hopkins was awarded his 24th of the season.
Edmonton quickly netted a second goal 58 seconds later when Kassian came around behind the net and pushed the puck inside the post just over the goal line. His unassisted goal came at 19:27.
St. Louis scored a power-play goal that deflected in off the skate of Perron six minutes into the third period. It was his 20th of the season, the fourth time in his career he has reached the plateau. The last time he scored 20 goals came during the 2013-14 season, when he was in his first season with the Oilers.
''It's a tough loss,'' said Edmonton coach Ken Hitchcock, who used to coach the Blues. ''We spent a lot of energy coming back in the game. The fifth goal was the killer for us. Against a good team like that, you can't take a penalty 200 feet from your net. Then we couldn't get it killed. We couldn't get the faceoff won.''
Maroon jammed the puck inside the right post at 13:22, making it 6-2 with his fourth goal in his last six games.
Schwartz scored his third of the night on a power play at 18:48.
''Obviously, it's going to give him confidence,'' Blues coach Craig Berube said. ''A player like that, that hasn't produced the way he wants to and the way we expect him to, it's tough. Getting a hat trick tonight will give him confidence for sure.''
Nugent-Hopkins did not like how the Oilers played.
''It's not just special teams,'' he said. ''They were outshooting us 23-5 at one point in the second. Our game is the best when we're forechecking and we're creating loose pucks. Tonight we just got away from that a little bit and the other team did exactly that and they got rewarded for it.''
NOTES: Blues RW Vladimir Tarasenko returned to the lineup after missing five games with an upper-body injury sustained March 7 against the Kings. Without him, St. Louis was 1-2-2. ... Connor McDavid had his streak of eight consecutive multipoint games snapped. McDavid remains three points shy of tying his career high of 108, set last season. ... St. Louis won the season series 2-0-1. ... Edmonton fell to 16-17-5 on the road. ... Binnington improved to 14-3-0 in his past 17 starts.
Oilers: Host the Columbus Blue Jackets on Thursday.
Blues: Host the Detroit Red Wings on Thursday.
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