While approximately 35,000 Serb refugees, trapped with the surrendered ARSK Kordun Corps, were evacuated to Yugoslavia via Sisak and the Zagreb–Belgrade motorway, the bulk of the refugees followed a route through the Republika Srpska, arriving there via Dvor in Banovina or via Srb in Lika—two corridors to Serb-held territory in Bosnia and Herzegovina left as the HV advanced. The two points of retreat were created as a consequence of the delay of a northward advance of the HV Split Corps after the capture of Knin, and the decision not to use the entire HV 2nd Guards Brigade to spearhead the southward advance from Petrinja. The retreating ARSK, transporting large quantities of weaponry, ammunition, artillery and tanks, often intermingled with evacuating or fleeing civilians, had few roads to use. The escaping columns were reportedly intermittently attacked by CAF jets, and the HV, trading fire with the ARSK located close to the civilian columns. The refugees were also targeted by ARBiH troops, as well as by VRS jets, and sometimes were run over by the ARSK Special Units Corps' retreating tanks. On 9 August, a refugee convoy evacuating from the former Sector North under the terms of the ARSK Kordun Corps' surrender agreement was attacked by Croatian civilians in Sisak. The attack caused one civilian death, many injuries and damage to a large number of vehicles. Croatian police intervened in the incident after UN civilian police monitors pressured them to do so. The next day, US ambassador Galbraith joined the column to protect them, and the Croatian police presence along the planned route increased. The refugees moving through the Republika Srpska were extorted at checkpoints and forced to pay extra for fuel and other services by local strongmen.