Acts 10:44-48

44 While Peter was still speaking these words, the Holy Spirit fell upon all those who were listening to the message. 45 All the circumcised believers who came with Peter were amazed, because the gift of the Holy Spirit had been poured out on the Gentiles also. 46 For they were hearing them speaking with tongues and exalting God. Then Peter answered, 47 “Surely no one can refuse the water for these to be baptized who have received the Holy Spirit just as we did, can he?” 48 And he ordered them to be baptized in the name of Jesus Christ. Then they asked him to stay on for a few days.

What happened here must have been a great shock to everyone, especially to those Jews who came with Peter. They had believed that Gentiles were unholy and could never be saved. But now they (all the Gentiles: Cornelius and his household) received the Holy Spirit, and they also were speaking in tongues (just as people were doing at Pentecost, which was an indication that the Holy Spirit had come into them).

Peter didn’t seem to be surprised at what happened. In fact, he ordered them to be baptized.