Someone hit garage door; tenant claims no knowledge; now what?

[Princesa Hansen]

Tenants in our townhome reported that their garage door was hit & damaged. It's clearly dented and broke hinges, so not fixable and needs to be replaced. However, they claim no knowledge of how it happened and don't want to be responsible for damages.

It clearly wasn't our negligence. And since it's a private driveway, most likely the person who caused the damages either lives there, visited someone who does, or was delivering something to them. This isn't normal wear and tear, and we clearly didn't cause the damages, so I believe the expense should be covered by the tenants. Anyone can claim ignorance, but it was damaged during their tenancy and likely related to their use of the home. 

We can look into auto coverage and rental coverage, but they want us to pay any deductibles. How would you approach this?