Francesco Cossiga first assumed the explosion to have been caused by an accident (the explosion of an old boiler located in the basement of the station). Nevertheless, soon the evidence gathered on site of the explosion made it clear that the attack constituted an act of terrorism. "L'Unità", the newspaper of the Communist Party on 3 August already attributed responsibility for the attack to neo-fascists. Later, in a special session to the Senate, Cossiga supported the theory that neofascists were behind the attack, "unlike leftist terrorism, which strikes at the heart of the state through its representatives, black terrorism prefers the massacre because it promotes panic and impulsive reactions."