What did the angels strike the men at Lot's door with?

Answer: Blindness

The angels pulled Lot inside and struck the men at the entrance with blindness, so they wearied themselves looking for the door.

“But the men inside reached out, pulled Lot into the house with them, and shut the door. And they struck the men at the entrance, young and old, with blindness, so that they wearied themselves trying to find the door.”— Genesis 19:10-11 (BSB)