The Upland City Council made the decision unanimously Tuesday night to place Robb Quincey on leave, but would not state the reasons for the action.
"The City Council is just asking prudently as good leaders of the community and wants to take all opportunities to reach a level of certainty that the community will trust what's going on in City Hall," said Upland City Attorney Bill Curley.
It is unknown when Quincey would return to his position as City Manager.
"It's indefinite," Curley said. "Certainly they won't want to drag it out, but there is no specific time."
Upland Finance Director Stephen Dunn will act as City Manager in the interim.