Zach Sanford also scored during the three fastest goals to open a game in Blues history. The flurry was the fifth-fastest three goals to begin a game in NHL history, and the fastest since December 1987.
''That was probably the quickest start I ever had in a hockey game,'' said Kyrou, who also had an assist in his first career multi-goal and three-point game. ''To be honest, I was a little surprised myself.''
David Perron, Kyle Clifford and Vince Dunn scored later as the Blues won back-to-back games for the first time this season. They hadn't played in four days after their game at Vegas on Thursday night was postponed.
Max Jones scored for Anaheim, which has lost two straight. The Ducks have scored just 15 goals in nine games this season.
''There were a number of minutes when we were certainly not our best,'' Anaheim coach Dallas Eakins said. ''There's lots of lessons to be learned there, and hopefully we're a very prideful group.''
Jordan Binnington stopped 23 shots for St. Louis against the NHL's lowest-scoring team in goals per game.
Kyrou, a 22-year-old Canadian forward in his third NHL season, scored just five goals in his first 44 games over two seasons. He has five more goals in eight games this season, and his 10 points have surpassed his entire total from last season.
''I think he's impressed everyone,'' Sanford said. ''This year he's just taken his game and his confidence to a whole other level, and it's great to see. He's gelling with his teammates and his linemates, and he's been a big part of it for us at the start of the year.''
Kyrou scored 20 seconds after the opening faceoff, and after Sanford added his goal inside the opening minute, Kyrou made it 3-0 and chased John Gibson with a breakaway.
Gibson skated swiftly to the bench and up the tunnel after Kyrou scored his second goal with minimal defensive resistance. The goalie has been the Ducks' best player again this season, posting two shutouts even while his teammates scored only 12 goals in their first seven games.
After Gibson gave up three goals on six shots, Ryan Miller made 21 saves.
Jones got his first goal of the season late in the first period for the Ducks, who have four goals in their last three games.
''The nice thing about having a back-to-back is you get to get back at it,'' Anaheim captain Ryan Getzlaf said. ''When you come out and lay an egg like we did tonight, you get to let it go.''
Washington set the NHL record for the fastest three goals to open a game on Dec. 19, 1986, doing it in 1:21. The Blues' opening flurry in Anaheim was the league's quickest since Detroit scored thrice in the opening 1:48 on Dec. 4, 1987.
The teams play again Sunday.
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