Unknown armed men detonate explosive device at café entrance in middle Gaza City

At app.
2am, on 28/12/2007, unknown armed men detonated an explosive device at the entrance of Al Aseel cafأ© which is owned by Mahmoud Abu Howeidy, in An Nasir street close to Palestine Bank .
The explosion caused severe damages to the shop's entrance and furniture.
No information is avaliable regarding the preparetors or the motivation behind this incident.