GRAPO, which has been inactive for several years, authorities said. There were no casualties in the explosions, which occurred within minutes of one another at around 4 a.m. (0300 GMT). A third bomb was later found planted in a tax office in the town of Alcobendas and was detonated safely outside the building, police said. All three devices were equipped with timers and were planted in bathrooms, officials said. The explosions tore through walls, wrecked ceilings and destroyed computer equipment. GRAPO, which stands for October First Anti-Fascist Resistance Group, was active mainly in the early years of Spain`s transition to democracy in the late 1970s after four decades of dictatorship under General Francisco Franco. It was blamed for dozens of killings in its campaign to establish a Marxist state. Most of its members have been in jail for years but a small number continue to stage occasional attacks. GRAPO`s last known action was the 1995 kidnapping of businessman Publio Cordon in the city of Zaragoza. Cordon`s family paid ransom and GRAPO claimed it later released him in Paris, but he has never surfaced.