On the morning of 28 June 1991, a suspicious package was delivered to the Sevilla-1 prison. It was addressed to the governor of the prison and bore a Valladolid postmark. The Civil Guard officer who first received it asked the mail service —comprising a number of prison officers and inmates— to check it in the X-ray scanner. The scan was unable to determine the contents and the police therefore called in bomb disposal experts.
The time was around 11.20 am, and in the adjoining room, relatives and friends of the inmates were waiting for prison visits. Suddenly, a bomb that had been planted in the package exploded, destroying the room. The explosion killed Raimundo Pérez Crespo, Manuel Pérez Ortega, Jesús Sánchez Lozano and Donato Calzado García. Another 30 people, including two children, were wounded. ETA claimed responsibility for the attack. Six ETA members were being held in Sevilla-1 prison and on the same day another member of the organisation was standing trial in the city.
Raimundo Pérez Crespo ran a stationery shop in Santander. At the time of the attack, he was waiting in the adjoining room to visit his brother, an inmate at the prison. He was taken to the Intensive Care Unit of the Virgen del Rocío hospital in Seville, where he died a few hours later.