Did I see portal to another dimension?

I am basically a no nonsense type of guy. But a few nights ago I was driving the country way from my friends house back to mine it was about 11.45ish. This area is very creapy old victorian homes with dead cotton wood trees mostly turn of the century and very hilly. Anyways I driving up to the old church with a graveyard. Something looked off. at first glance I thought the churches doors were open. I thought that was wierd slowed down and got a better look. It was a large black square with rounded edges in mid air illumanating the look of depth. I have never even heard of someone seeing someting like this. I then got very close to it in as I was driving and A big white flash happend and it went away. It was very wierd so whats your guy's take on this?