The small port town was rocked by the loud explosion at sunrise.
Firefighters arrived just before 5:00 am.
They searched through the rubble of a collapsed two-storey building, recovering the bodies of a 68-year-old man from Livorno and his 76-year-old wife.
The three people rescued from the rubble are a local family, two elderly parents and a 46-year-old daughter, according to Italian news agency ANSA.
The father and daughter were airlifted to the Cisanello Hospital in Pisa, with burns to 90 per cent and 50 per cent of their bodies respectively.
The mother suffered minor injuries.
Police said the explosion was caused by a gas leak in the building.
The town’s mayor, Angelo Zini, said the incident was “a tragedy”.
