 On 4 March, ELAS forces from Siatista, augmented with Reserve ELAS members from the surrounding villages, some 200–250 men in total, ambushed an Italian convoy heading for Grevena from Korce via Florina and Kozani.The ambush took place in the narrow pass of Bougazi between the mountains of Sniatsiko and Bourino, at the location known as Vigla, some 3 km from Siatista itself.The partisans were armed with shotguns and antiquated Gras rifles, axes, and damascened knives, but were able to knock out the first and ninth lorries in their opening salvo, trapping the bulk of the convoy; only the tenth lorry, at the rear of the column, managed to turn around and escape.