Six people died on Sunday, including a woman aged 103, after an earthquake measuring 5.9 on the Richter scale - almost as strong as a major 2009 quake - hit northern Italy, dpa reported.
An aftershock with a magnitude of 5.1 hit the area on Sunday afternoon, the news agency Ansa reported.
Old buildings including churches and towers collapsed or were cracked in. An estimated 3,000 people were left homeless.
The inital quake hit the region of Emilia-Romagna at 4.04 am (0204 GMT). The epicentre was 36 kilometres north of the city of Bologna and had a depth of around 10 kilometres, according to the National Geophysical and Volcanic Institute.
Television images showed footage of collapsed buildings and churches, with rubble covering the streets.
The worse hit were the towns of San Felice and Finale Emilia, where many historic buildings were severely damaged. The quake also shook the city of Ferrara, listed as a World Heritage site by UNESCO on account of its Renaissance palaces.
Four people died when the factory buildings they were working in collapsed.
Two workers died in a ceramics factory in Sant'Agostino, near Ferrara, while a third died at a metal-working factory in the same area. The fourth was killed in an industrial area in the town of Bondeno, around 15 kilometres from Sant'Agostino.
A 37-year-old German woman died in Casale. She developed breathing difficulties, possibly because of a panic attack triggered by the earthquake, lost consciousness and could not be revived, Ansa reported.
A woman aged 103 was also found dead in Sant'Agostino, according to Ansa. She had been hit by pieces of a falling ceiling.
The television channel Rai put the toll of injured at around 50.
Thousands of people remained on the streets in the early morning, unwilling to return indoors.
The earthquake was felt as far away as Milan and Venice, though no damage was reported there.
The earthquake was almost as strong as one measuring 6.2 on the Richter scale which hit much further south at Aquila in April 2009, killing nearly 300 people and leaving 60,000 homeless.
Seismologists voiced surprise that such a big quake had hit Italy's Po valley.
Winfried Hanka, a geophysicist at the GFZ geo-science centre in Potsdam, Germany, said German seismologists estimated the force of the Emilia-Romagna quake at 6.1, more than the Italian estimate.
"Italy as a whole is constantly at risk from earthquakes," he said. "But some regions are less at risk." Emilia-Romagna had traditionally been marked as region where tremors were less common. d