Police said yesterday they were sure that a bomb that went off outside a suburban shopping center on Thursday was not aimed at damaging an American Express branch in the center as was initially suspected, as it was placed too far away to cause damage to the bank, which was closed at the time. Police believe that the bomb at 292 Kifissias Avenue at Neo Psychico may have been destined for another site but that, for some reason, the person transporting it abandoned it. They also suspect that it may have involved a settling of accounts with local shopowners, although the latter said they had not received any such threats. Forensic tests have not yet provided conclusive evidence regarding the type of bomb or the manner in which it was detonated. Police are also examining footage from surveillance cameras in the area. The makeshift device, placed on a bicycle carrier at the entrance to the underground car park, caused extensive damage and slightly injured two women. There was no warning of the explosion, which also blew out the windows of a passing school bus carrying pupils.