Large Bus Like Dark Gray Rectangular UFO

I was traveling west on Highland Ave to pick up our dog’s arthritis medication and saw coming out of the cloudy sky a dark gray aircraft that resembled a large bus due to its rectangular shape and it was traveling north to south. I thought is this a blimp ? Realizing that I have never seen a rectangular blimp in my life. This flying object was no aircraft I was familiar with. It seemed to be flying faster than a blimp yet slower than a plane. I can’t say how far the objects distance was from me but it wasn’t very high in the sky. I pulled into the veterinarians office parking lot in hopes of capturing a video or picture but the object was now hidden behind large Perris Hill Park Trees. I have been searching google to see if any one else witnessed this UFO here in San Bernardino California but there is no reports so far. I know I wasn’t the only person to see this UFO. I anticipate some sort of reports to confirm that there was definitely a strange flying object in our skies!!