Shadow Figure Wants In - No Way!

When I was coming back from my early morning run (6 am, still dark out) this morning, I saw this thing/shadow figure crawling up our front steps. It was still pretty dark out, but I could see this hump-backed shape on the stairs that led to our front door. It was there long enough for me to see it, then it disappeared. As I came closer, it looked like the air in front of the stairs was being distorted, the way heat rises off of asphalt in the summer time. Then I noticed something was ducking behind our mailbox and quickly sticking its head out on either side of it. I walked a few cool down laps up and down the street, watching what was going on in front of the house the whole time. I avoided going up the walkway to the stairs because the air was still being distorted. I'm not sure if something wanted me to walk through that so I would bring it into the house, but I didn't take that chance and instead went around and then up the stairs. I'm not sure what this thing was but I knew it wanted in.