A man who below himself up inside a mosque in the eastern city of Qatif on Friday was a Saudi national affiliated with ISIS, the Saudi Interior Ministry said Saturday.The man, called Saleh al-Qashaami, was wanted by Saudi security agencies, the official Saudi press agency quoted the ministry spokesman as saying.According to him, al-Qashaami blew himself up inside a Shia mosque in Qatif on Friday, leaving 21 people dead and 101 others injured.He added that he was a member of a cell, noting that 26 members of the same cell had been arrested a few days ago.The ministry spokesman went on to note that all 26 members were Saudi nationals.He said five cell members were involved in an armed attack on a police patrol southern Saudi capital Riyadh on May 8.He added that the attack had left one Saudi soldier dead.