First: File a Police report ASAP. Every detail matters no matter how big or small. A police report will add to your documentation/evidence if you go to trial. (hopefully you don't let it get to that point)
Make clean copies of the report. keep the original in a plastic page protector sheet in a 3 ring binder.
Keep a copy [of the report] for the case, the landlord, the courts and your possible attorney.
Next, write a FORMAL respectful letter [again keep copies of everything!] to your landlord. If you need help writing the letter, you can email me and I will be glad to help you. The letter should kindly state that your garage was damaged through no fault of your own, that you have taken the steps to take action against the possible criminal/crime, give him a copy of the police report with the letter, and request that you guys please work things out, before things escalate, TRUST ME YOU DON'T WANT TO BE EVICTED OVER A $100 GARAGE, YOU WILL LOSE AND END UP LIVING IN SOMEONE'S GARAGE IF YOU DON'T ACT ACCORDINGLY.