The strongest earthquake to hit Italy in three years has left at least six people dead, 50 others injured and several factories and historical buildings in ruins.

The magnitude 6.0 quake struck near Bologna at 2am local time on Sunday morning.

Two people were killed when a ceramics factory in Sant'Agostino caved in, and another died in the collapse of a factory in Ponte Rodoni do Bondeno.

Sky News said at least 6 people were killed in total, and that 50 people had been injured.

Rescue teams are now searching the area after reports that survivors are buried under rubble.

The towns of Bologna, Modena, Ferrara, Rovigo, Verona and Mantua were all affected.

There were chaotic scenes when thousands of people rushed into the streets when the quake hit, and residents were warned by officials to stay out of their homes as heavy aftershocks of up to 5.1 shook the area.

Local Modena resident Matthew Hatton told Sky News that he was in a bar when the owner suddenly told everyone to get out.

He said: "There were a few people crying. It was quite a strange experience. There were car alarms going off - that kind of thing. For four or five seconds it was really quite a strong one."

News agency Reuters reported severe damage to historic buildings in San Felice Sul Panaro, close to where the earthquake erupted.

Its 14th century Estense Castle and main church were both heavily damaged, while one of the towers of its renowned medieval castle was thought to be in danger of collapsing.

The last time Italy was hit by a major earthquake was in 2009, when a 6.3 magnitude quake struck L’Aquila, the capital of Abruzzo in the centre of the nation, killing 308 people and damaging between 3,000 and 11,000 buildings.

The devastation left 40,000 people homeless.