When they came down to him; either in the city, into which they easily got admission, when they declared that the only end of their coming was to take Elisha; or in the field without the city, whither he went to meet them. He smote them with blindness; not with a total blindness, that they could see nothing, for then they would not have followed him; but with a partial blindness, that they could not distinctly discern the man they sought; which might be by some alteration made by God in their brain, or in the air. See Poole on "Genesis 19:11".
Related Commentaries of 2 Kings 6:18
2 Kings 6:18
18 And when they came down to him, Elisha prayed unto the LORD, and said, Smite this people, I pray thee, with blindness. And he smote them with blindness according to the word of Elisha.