An injured animal may not be able to get home or may choose to withdraw into a quiet place. The sooner the cat can be gotten to emergency care the better its chances of survival. Sometimes cats climb into moving vans or parked cars and are not found immediately. Ask neighborhood kids if they have seen anything. Give them your name and number.
Kids can be a great source of neighborhood goings-on.
Now put up posters around the neighborhood and take them back to those neighbors you have already contacted if you weren't able to supply a poster earlier. Vets will stabilize injured cats before they are taken into the animal shelter. If you offer a reward, beware the hostage-taker or bogus calls. Your description may not be sufficient to help an attendant identify the cat over the phone. Ask if any overflow cats are being held in the dog area.