"Some towns in the area have been virtually destroyed in their entirety," a somber Gianfranco Fini, speaker of the lower house of parliament, said before the chamber observed a moment of silence.
The Italian news agency Ansa, quoting rescue workers, said the death toll had reached 92 nearly 12 hours after the quake struck.
Most of the dead were in L'Aquila, a 13th-century mountain city about 100 km (60 miles) east of Rome, and surrounding towns and villages in the Abruzzo region.
Houses, historic churches and other buildings were demolished in the worst quake to hit Italy in nearly 30 years. Hundreds of people were injured and some 15,000 buildings declared off limits.
"I woke up hearing what sounded like a bomb," said Angela Palumbo, 87, said as she walked on a street in L'Aquila.
"We managed to escape with things falling all around us. Everything was shaking, furniture falling. I don't remember ever seeing anything like this in my life," she said.
Interior Minister Roberto Maroni visited the area and said the death toll had surpassed 50.
Luca Spoletini, a Civil Protection Department spokesman, said the quake may have made up to 50,000 people homeless. Some 26 cities and towns were seriously damaged.
In the small town of Onna alone, 10 people were killed, said a photographer who saw a mother and her infant daughter being carried away in the same coffin.
Prime Minister Silvio Berlusconi cancelled a trip to Moscow and declared a national emergency, which would free up funds for aid and rebuilding. Pope Benedict said he was saying a special prayer for the victims.
Older houses and buildings made of stone, particularly in outlying villages that have not seen much restoration, collapsed like straw houses.
Hospitals appealed for help from doctors and nurses throughout Italy. The stench of gas filled some parts of the mountain towns and villages as mains ruptured.
Residents of Rome, which is rarely hit by seismic activity, were woken by the quake, which rattled furniture and swayed lights in most of central Italy. It struck shortly after 3:30 a.m. (0130 GMT) and registered between 5.8 and 6.3 magnitude.