Slowed down, stopped for maybe a second or two, then sped up and "disappeared"

I'm a contractor based in the tri-state who was doing some work in the area. I stayed in the truck while my coworker went inside to grab a few plumbing supplies. I was listening to music looking up into the sky, when almost directly in front of me, at plane altitude, a white, disk shaped object slowed down into view from my left, stopped for a second or two, and then accelerated at an unbelievable speed to my right. I looked around and even got out of the truck but it was already gone. I'm not really into UFOs but one of my friends suggested I submit a report on what I saw