The stoning of Stephen ushered in overt persecution of the early church -- beginning with the Christians from a Hellenistic Jew background. Some, like Philip, were driven to Samaria. The Samaritans received the gospel with enthusiasm and joy. They received the gift of the Holy Spirit in a special (i.e. no longer normative) way that served to authenticate the prophecy of Acts 1:8.

Many commentaries shed light on this, potentially tricky, passage. Here is some supplementary material.