Acts 19:23 says that there arose no small disturbance about the Way (a means of referring to Christians). It seems that it was begun by Demetrius, a silversmith in Ephesus whose business was making silver models of the temple of Artemis (Diana in Roman mythology). Paul’s preaching was convincing so many people to follow Jesus and abandon the worship of Artemis that it was having a major economic impact on not only Demetrius, but the entire Ephesus economy. Verse 27 states Demetrius’ position very well, “This poses a danger not only by discrediting our trade but also by completely dishonoring the great goddess Artemis. The whole province of Asia—indeed, the entire civilized world—worships her, but her splendor will soon be extinguished.” (CEB)
The craftsmen began to shout “Great is Artemis of the Ephesians!” rush into the theater where town meetings were held, grab two of Paul’s companions, throwing the city into turmoil. Luke states the crowd was in a state of confusion, some shouting one thing, others shouting something else, and most of them not knowing what’s going on. Alexander, a Jew tries to speak but when the crowd realizes that he is a Jew they all shout “Great is Artemis of the Ephesians” for two hours!
The city manager is able to bring order, and even though this disturbance has been going on for a couple of hours he still believes if they disburse now they won’t be seen as was having had a riot.
The riot when I was in high school was a lot shorter than 2 hours. The Ephesians apparently believe the city manager and disburse. In Acts 20:1 Luke calls it a riot.