Given your location, it is a Kinglet. And thank you for caring! Here's an example of the stickers I was talking about
FYI, they make stickers you can put on your windows to help birds see them more clearly, and they’re cheap + easy to apply. I got these a while back and haven’t had any collisions since: https://www.amazon.com/WINDOWALERT-WA-MAPLE-WindowAlert-Maple-Decals/dp/B001BO6EMC
Was it a glass or plastic door?
If so you can get a set of these translucent decals. They stick to the glass without adhesive, and help the birds understand that there is a barrier there.
You can get stickers like this for the windows! https://www.amazon.com/dp/B001BO6EMC/ref=cm_sw_r_cp_tai_B9RpBbDC5YZNC
Some people run streamers on their windows but I think this is much less intrusive.
tough to say for sure, as nightjars can be very difficult to ID visually and often have a lot of variability in color between species, but I'm leaning towards this being a female or immature Chuck-will's-widow, based on the lack of a prominent black crown stripe often seen in Whip-poor-will, and on the color of the tips of the outer tail feathers: Chuck-will's-widow has more caramel-colored, less contrasting tips to the outer feathers, while Eastern Whip-poor-will's outermost tail feathers are tipped in a paler buff or tan.
And yes, please put up some window decals to prevent more window strikes :) Some nice ones are available on Amazon and are pretty cheap