Why is john proctor arrested in The Crucible?

In the play "The Crucible" written by Arthur Miller, John Proctor is arrested at the end of Act II due to false accusations of witchcraft. Abigail Williams, who is having an affair with John, accuses him of partaking in witchcraft to divert attention away from her own involvement. Reverend Hale, who has come to Salem to investigate the witchcraft, believes Abigail's testimony and orders Proctor to be apprehended and confined in a jail in Boston.