During the late hours of 30 April, a group of four Provisional IRA members held a family hostage in Killeen and stole a mechanical excavator. This was to be used to build a makeshift ramp up to the Dublin–Belfast railway line, which drew parallel to the Dublin–Belfast motorway (M1). At the same time, other IRA members stole a Renault Master van in Dundalk, which was then loaded with 2,200 lb (1,000 kg) of home-made explosives. The van was fitted with wheels that could run on the rails. The excavator moved up the ramp and lifted the van onto the railway. The van was then driven some 800 metres north and a mile-long wire attached to a triggering device was added to the bomb. Meanwhile, IRA members in support set up roadblocks on both sides of the border to keep people away. The IRA unit who