A week before this event, another was targeted and 20+ people were killed. Taking security a bit more seriously , people asked women to stay home and not to come to Friday prayers (easier to control security in a predominantly male-ish society). The Isis guy did not know this bit of info (no women in the mosque), so his appearance as a woman in a veil raised immediate suspesion.
Two security volunteers were reported killed immediately because had their bodies were almost intact. Two others were not detected until later because their bodies were totally scattered. Bits and pieces of flesh were thought to be of the terrorist until it was realized later to be from two other guys helping the volunteer guards.
Until Tuesday evening (4 days later) there were calls to neighbors of the mosque to search around their homes for any human remains.