Residents called police about midnight to report seeing the bear from the Zooz Nature Park, about five miles from the popular Crystal Beach in Ontario.
Darlene Crosby told CHCH television she let her dogs out and saw the bear when they started barking. Police asked Crosby and her husband to leave their home as a precaution.
As a police helicopter equipped with thermal imaging gear circles the area, police asked people living near the zoo to stay indoors and to keep their pets inside.
The Zooz Nature Park is home to more than 400 species of animals.