The explosions occurred at the Paolelli fireworks factory in the town of Tagliacozzo at around 2pm on Wednesday afternoon, Corriere della Sera reported.
Rescuers have recovered three bodies from the rubble and another person is still missing. Their identities have not yet been confirmed. A further three people have been rescued.
Witnesses reported hearing three violent explosions within the space of a quarter of an hour and residents several kilometres away reported feeling tremors, sparking fears of an earthquake.
One witness, who was exercising in a gym just 500 metres from the factory, described the explosion as being like “the end of the world”.
“We left the gym when the third very violent explosion happened which flung us to the ground,” he told Italian news agency Ansa.
Speaking near the scene, Tagliacozzo’s mayor Maurizio Di Marco Testa told Ansa: “I was the first to arrive along with the police. I saw and heard the third explosion at the scene, it was like an earthquake."
The area has now been cordoned off for fear of more explosions.
This isn’t the first time in Italy that a fireworks factory has exploded. On July 25th 2013 a similar incident occurred in Città Sant'Angelo in the central province of Pescara in one of the largest firework factories in Italy, causing four deaths. And on September 12th 2011 an explosion at the Cancelli fireworks factory in the town of Arpino in the central province of Frosinone killed six people.