If possible, safely contain or confine the cat so it doesn't run away.
Look for a collar with tags that identify the cat and owner.
Call animal shelters to ask about lost cat reports that match the cat found.
Make found cat signs with the cat's description to post in the area.
Share found cat info and photos on neighborhood groups and pages.
A vet can scan for a microchip to identify registered lost cats.
Feed, water and safely confine the cat until the owner is located.