On that Sunday morning a Civil Guard patrol was sent from the station in Mondragon (Guipúzcoa) to the sanctuary of Our Lady of Aránzazu to remove a Basque flag, which at the time was banned. The civil guards inspected the area, fearing that the flag might be wired up to some explosives, but it was only joined to a bag with sand in it, and so they removed the flag and headed back towards the station in Mondragon.
The real booby trap was not far away. Just one kilometre from the sanctuary, ETA had hidden, in a bank on the right-hand side of the road, a powerful bomb, marked with a red mark so that the device could be set off when the Civil Guard Land Rover was passing by. The device was detonated from a remote-control unit and the Civil Guard vehicle took the full impact of the blast and blow about twenty metres off the road, rolling over several times. Esteban Maldonado Llorente, Jesús Pascual Martín and Juan Moreno Chamorro were killed instantly and their bodies suffered multiple injuries. Another two officers were seriously injured.
Esteban Maldonado Llorente was 20 years old and unmarried. He was originally from San Pedro de Mérida (Badajoz).