Yauhen Massalski's layup gave San Diego a 71-70 lead with 25 seconds remaining. Childs answered with an alley-oop dunk with 11.1 seconds to go, then Braun Hartfield missed a corner 3-point shot to end it.
Haws had 10 assists for his second career double-double. Childs grabbed a game-high seven rebounds. Zac Seljaas added 10 points for BYU (21-7, 10-3).
The Toreros have lost six of their last seven games.
BYU hosts Santa Clara on Thursday. San Diego plays at Saint Mary's on Saturday.
For more AP college basketball coverage: https://apnews.com/Collegebasketball and http://twitter.com/AP-Top25
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