Police in Tanzania have arrested 15 people in connection with the series of acid attacks in Zanzibar.  The victims have included a Roman Catholic priest and two young British women who had volunteered with a humanitarian group.

Zanzibar police commissioner Mussa Ali Mussa says some of the suspects are teens who wanted to join the Somali militant group al-Shabab.  They’re also investigation al Qaeda links to the adults.  Investigators seized 29 liters of acid as evidence.

The most recent attack was last Friday, when elderly priest Joseph Anselmo Mwagambwa doused with acid by men on a moped as he was leaving an internet cafe in the island's old town. 

Last month, 18-year-old British women Kirstie Trup and Katie Gee were burned in a similar attack, so terrible they had to be airlifted to Dar es Salaam for medical treatment before being evacuated back to England.

Although attacks on foreigners are rare in Zanzibar, although tensions between the majority Muslim population and Christians have been on the rise in recent years.