They were referring to Jesus, not to some unidentified prophet. "Raised" here is an idiom for "caused to become." This can be stated in active form. AT: "God has caused one of us to become a great prophet" (See: [[rc://en/ta/man/translate/figs-activepassive]]) (See: [[rc://en/ta/man/translate/figs-idiom]])
"This news" refers to the things people were saying in verse 16. This can be stated in active form. AT: "People spread this report about Jesus" or "People told others this report about Jesus"