Smoke

I was driving home mid-day Sunday, and I encountered a big white cloud of smoke the length of my city block. I stopped twice to make sure I could see through it safely while driving. It smelled a bit acrid, like burning rubber or something. I thought it must be from a malfunctioning vehicle that had driven ahead of me. But I never saw what vehicle that might have been.

A little while later, a fire truck came down my block, and proceeded to drive around the area a bit. I think someone had made a 911 call about the smoke. But the firefighters couldn't seem to find the source.

Where's there's smoke,
Fire is expected.
But this time
It couldn't be detected.