καὶ ἐβαπτίζοντο (they were being baptized) ὑπ᾿ αὐτοῦ ἐν τῷ Ἰορδάνῃ.

καὶ ἐβαπτίζοντο (they were being baptized) ὑπ᾿ αὐτοῦ ἐν τῷ Ἰορδάνῃ.

And they were being baptized by him in the Jordan.