Lights emerge from thundercloud

I was having a fitful sleep as a result of a thunderstorm that was blowing through our city in the middle of the night.  At about 3:00 a.m. a bright flash of lightning and a loud thunderclap startled me awake again.  Looking out our bedroom window, I could see that most of the storm had passed from the southwest and was now mostly east of us.  As I was looking, I saw a white light to the south-southwest about as bright as Mars has been these past few weeks.  I thought, a star, that means the storm must be breaking up and I can get a few hours of sleep.
But then, I saw that it was moving and after a few seconds I thought perhaps it was the ISS, based on how fast it was going and the direction it was going - mostly eastward, but with a slight northerly track.  But I also thought that it didn't appear as bright as when I saw the ISS pass overhead a couple weeks ago.  But then the light began a gradual turn and after about two or three seconds continued to the north or to the north-northwest.  Well, that's peculiar I thought, and sat up to look more intently at the sky.  The light disappeared out of my view, blocked by the window frame.
Then another light appeared, from more or less the same region of the sky as the first.  It was moving about the same speed, going slightly to the southeast.  Then it, too, turned and moved off to the north.  Up until this time, I thought I was viewing these lights against a clear sky, having thought the storm had moved off to the east.  But at the next moment, a bright flash of lightning in the east lit up the whole sky and I could see that the entire sky was filled with clouds, with no breaks to see the stars, and the area from which the lights had appeared was in fact a large, dark thundercloud.  Reviewing the public weather radar some four hours later, I would guess that the cloud could have been between 20 and 60 miles away, although at the time I had the impression that it was almost upon the city, less than 5 miles away.
As I continued to watch, a second or two after the lightning, a third light appeared from the same area of the sky and continued on a path similar to the first one, at first heading east but then turning to the north or northwest.  I watched the cloud for two or three minutes but saw no additional lights, then went back to bed.