to purrs
i thonk for your own peace of mind and also the cats safety you need to find them.
cats are very good at finding places to hide that we think are too small for them to get into and as christine says have you had any windows open.
if the latter is the case then i would put some food down outside to try and attract them, cos hunting and shouting for them will be useless.
how old are they?
my campaign would be to shut all doors of every room, stop all noise and activity and search each room individually. under between and on top of things , behind curtains, a very thorough searcc, do it quietly and carefgully and if you find them do not disturb but just talk quietly, leave some food and water and a litter tray, shut the door and let them explore one room at a time in peace and quiet.
I hope you find them in the house and if any windows are open, make sure the cats cant get in that room until they are closed. If they are not in the house then its time to tell the place you got then from because they may be heading back there.
You will need to put up posters, advise all local vets etc etc