(Compass) – Police on the small, predominately Muslim island of Zanzibar off the coast of Tanzania have stepped up investigations and arrested three suspects after two Catholic churches were destroyed and a small Protestant church was set ablaze in a recent spate of violence in mid October. According to Roman Catholic Bishop Augustine Shao, it was not clear who had carried out the attacks. We had no sour relationships with our [Muslim] brothers and sisters. You may find one person talking against another religion but it is not a common thing. The local Guardian newspaper reported that the Zanzibar Mufti, Sheikh Harith bin Khelef, had condemned the attacks on churches in the Unguja South Region and called on Muslims in Zanzibar to respect freedom of worship. Early this year, tensions increased on the island when an Islamist group held an illegal rally. Zanzibar is a generally peaceful, semi-autonomous territory of Tanzania governed by secular political parties.