I'd grab whatever weapon of oportunity was around (probably a hammer) and causiosly scout it out.
This tread reminds me of a funny story though. My wife and I have encountered a break in in progress. We where babysitting my mother in law's house while she was in Cali and we where the only ones in town. Anyway, we heard some really odd noises coming from the garage. We went around to the side of the house to where the walk in garage door is and spotted someone leaving the garage with a crowbar in hand. Here is the crazy part; While I was soaking in what I was witnessing, my wife, who is not a MAist of any sort, bum rushed the robber and tackled him before I had a chance to even take a step towards him :erg: . I snapped out of my shock, grabbed the guy (who was already giving up under the pressure of my wife's "enthusiasm") and kept him there until the police arived. We got the job done, and the police caught the other robbers (one of whom had a gun!) who had gotten away before we caught who was apparently the last one out.
Not the brightest way to go about things, but luckily things worked out in the end.