IS spokesman Adnani killed
Islamic State's most prominent and longest serving leaders was killed in airstrike.
United State defence official said Abu Muhammad al-Adnani's vehicle traveling in Syria town of al-Bab hitted by US airstrike.
Adnani reporte to be the last living senior member along with self appointed caliph AbuBakr al-baghdadi.
Adnani was IS spokesman most visible member.