Kitchen broke a tie in the 70th minute, scoring on a header off a corner kick.
DeLeon opened the scoring in the 54th minute, and Luke Moore tied in the 60th.
Bradley had a good scoring chance in the 34th minute, but the U.S. midfielder's shot went wide.
United improved to 8-5-4, and Toronto dropped to 6-5-3.
WHITECAPS 1, SOUNDERS 0
Sebastian Fernandez scored on a long shot in the 12th minute in Vancouver's victory over Seattle.
Major League Soccer-leading Seattle dropped to 11-3-3 with the loss that snapped its winning streak at three games. Vancouver improved to 6-3-7.
Copyright 2014 by The Associated Press
This story is from ESPN.com's automated news wire. Wire index
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