The children -- ages 1, 3 and 5 -- were severely dehydrated, but otherwise seemed to be well.
Woo was last seen on surveillance video Monday with her three children.
Her husband, Brandon Woo, said there were no domestic issues.
"I think something happened, and it happened on the road, didn't happen near our neighborhood, because if it was in our neighborhood, someone would have seen it," Brandon Woo told KTVT.
A medical examiner will determine the cause of death for the mother.