Grey Spheres flying fast, and low above city, appearing out of nowhere and disappearing into nothing.

My fiancé and I stepped outside our business for a cigarette. We run an exotic animal rescue and actually live in the back, there is an apartment. We were talking and I was looking at the sky, the next I thing I see is 5 grey, metallic looking spheres flying very low above our business and off into the distance disappearing. When the spheres first appeared they where in an uneven triangle formation then all switched positions, some overlapping others( looked higher up in the sky). The whole event only look seconds and my fiancé saw a large flash in the sky afterward. I’ve gone through a few options of what they could such as drones or helicopter, they made absolutely no noise and it was extra quiet when they went by. They didn’t have any lights, and I got a clear shot from how low some dropped to when they split from the triangle formation. Some of our animals have been acting spooked, or even just on edge since the incident occurred. Which is odd because we have no windows in our unit, so they wouldn’t be able to see anything anyways. Sometimes you can tell if it’s man made, or even the government…this time I have no idea what I even saw, hence my reason for this report.