John Gill Commentary Luke 8:33

"And the demons came out from the man, and entered into the swine: and the herd rushed down the steep into the lake, and were drowned." — Luke 8:33 (ASV)

Then went the devils out of the man
Being obliged by the power of Christ, sore against their wills, having had possession of him a long time:

and entered into the swine ;
possessed them:

and the herd ran violently down a steep place into the lake ;
that is of Gennesaret; or the sea, as the Syriac and Persic versions read; that is, the sea of Galilee, the same with the former: and were choked ;
in the waters, and died, as the Ethiopic version adds.