A vehicle containing 250 kilograms (550 lb) of ammonal was parked beside the main Guardia Civil barracks in the city of Zaragoza, Aragon, Spain; its explosion killed 11 people, including 5 children.

Following the Barcelona bombing, ETA's call for talks with the government of Felipe González was rejected and, on 5 November 1987, the Pact of Madrid resulted in an agreement between the main Spanish political parties to release a joint statement rejecting the legitimacy of ETA to speak on behalf of the Basque people and ruling out negotiations until the group had formally disarmed.

[7] At 06:10 on 11 December, a Guardia Civil officer stationed at the entrance to the barracks noticed 2 men parking a Renault 18 in front of the building.

[8] Before the officer had had time to wake those sleeping, the 250 kilograms (550 lb) of ammonal exploded, making a huge hole in the wall and instantly demolishing all four floors.

[1] The rescue effort continued through the night and, at 13:45 the following day, the last bodies, those of Ángel Alcaraz and María Dolores Franco, wife of a policeman, were pulled from the rubble.

Although no journalists entered the Basilica, photos of the coffins of the three-year-old twins appeared on the front pages of most national newspapers the following day, leading to strong anti-ETA sentiment.

[15] At the subsequent trial, it was revealed that the direct order to execute the Zaragoza attack had come from the Artapalo collective leadership and had been communicated by Josu Ternera.

The explosives expert named Joseba Arregi Ersotarbe, alias Fitipaldi, was responsible for assembling the device and delivering it to the bombers.

Francisco Mujika Garmendia, alias Pakito, monitored and produced a sketch of the barracks, giving the direct order to attack it.

Henri Parot parked the vehicle beside the entrance to the barracks while Esnal activated the mechanism that triggered the explosion in one minute and fifteen seconds, just long enough to enter and escape in the Peugeot 205 in which his two accomplices were waiting nearby.

[4] On 11 December 2007, to mark the 20th anniversary of the attack, a wreath-laying ceremony took place at the park, which was attended by Pascual Grasa, who was on guard at the entrance during the bombing, and seriously injured in it.