We have had a yard break in 2 gates had heavy padlocks cut, 12 saddles stollen tack room cleared out, including my brown wintec 17.5 which has slices on the cantle and my friends 30 year old tan jumping saddle.
there have been warnings on facebook and Horsewatch near us saying "suspicious" males have been seen around yards locally. Its very sad but it seems the only way to keep tack safe is to keep it at home, a pita but at least you know it'll be there when you want it I really hope you are able to make your stuff too hot to handle and get it back.
Beware, if they have taken old tatty tack, they may wait until you replace it and come back. Make sure that you improve your security/keep expensive tack at home.