Cats are notorious for not wanting to be confined (and if one gets it the others will rebel).
This is what I had to do to get my cats into carriers -
* Put each one in a separate room before getting out the carriers. (if a cat even sees a carrier it may rebel) * Tightly close doors to each room so cats can't escape (this included closet, cupboard, and other such doors in room as well). * Put one cat into carrier. (if they hate carriers, you may have to be sneaky - and wear long sleeved clothing) * Close door to room leaving cat in carrier inside. (if they howl it will alert the other cats to hide) * Repeat on remaining cats.