It was the third goal in two post-season games for Bruin.
The Dynamo remained undefeated against the Eastern Conference regular-season champions in four meetings this year.
The second leg will be in Kansas City to determine a berth in the Eastern Conference championship series against either D.C. United or Red Bull New York.
Couple mistakenly served bag of cash at McDonald's drive-thru
Exploding whale video goes viral on Internet