I would think the best way to handle it would be to tell the owner what happened and have a quote ready to tell him or her how much it would cost to fix. I do not think the tenant is responsible. I think it will be hard to track down who shot the bb and have them pay for it. I would probably get it fixed ASAP and have the owner pay for it. Then try to get the parent of who shot the bb to reimburse you.
I would tell the owner to call the police and file a report and get back to me with a copy of the report
Broken windows are usually the owner’s responsibility unless you can prove the tenant caused the damage. In this case, it doesn’t sound like you can prove that the tenant caused the damage, so it’s going to be on the owner to cover the cost of the repair.
Additionally, since it’s a Section 8 property, I’d recommend getting it fixed before the next inspection because a property could be failed for a broken window.
Owner is responsible for the repair unless they caused it.
I once had the same thing happened. Tenant called and reported a broken window. Said no idea how it happened, just he came home one day and window's broken. He even said it may be my lawn guy broke it while mowing may be the mower kicked up a pebble that hit the window...
I schedule a window company to repair the glass, he was not home that afternoon, I let the window guy in, during the repair, his daughter came home after school, 8 or 9 year old, she said "I am so sorry I broke the window I hope you are not mad at me..."
So she told her dad she broke the window, her dad lied to me about the window was broken and suggested may be my lawn guy did it. I was given a choice of either paying for the window myself or getting her daughter in trouble by contradicting her dad. I ate the $150 that one time. However months later when the lease was up and there were other items I deducted from his security deposit, he protested. I mentioned paying for the window I knew her daughter broke, that shut him right up.
I would want a copy of the police report and I would want my window guy to verify that it was in fact damaged from the outside. Then I would expect the owner to cover the cost.