I've thought about all the possible explanations; lightning, explosions, etc. but none seem to make sense considering it was a clear night with no clouds, there was no sound ( I know because my windows were down in my car) and from where I was on the highway, the light came from the ground, not actually the sky. The flash was just so bright that it illuminated the sky. A close friend of mine also saw the flash from about 5 miles away. We've been texting all afternoon about what it may have been or to see if anyone else other than him, my husband or myself saw it last night.
What's weird is that I have seen this before, and in the same area of town (which is fairly residential). A few years back, at around the same time of night, I was heading home and saw the flash from the horizon while I as on the highway. I'm sure once an explanation is given, it will all make sense, but till then the incident is going to continue to weird me out.