Rome, May 20 (IANS): A 5.9-magnitude earthquake rocked central Italy in the early hours Sunday, killing four people and injuring 50 others.

The earthquake had its epicentre between the cities of Ferrara and Modena at a depth of 6.3 km. A series of aftershocks were felt in many northern cities including Milan, Turin and Venice, Italy's National Institute of Geophysics and Volcanology said.

Three workers, one of who was a young migrant, died when two factories collapsed near Ferrara city in central Emilia Romagna region.

A 37-year-old woman died of a heart attack during the quake, while another worker of a local foundry whose roof had collapsed was missing, Xinhua reported citing Italian news agency ANSA.

At least 50 people were injured, state-run Rai television reported.

Thousands of people rushed out in panic to the streets in various places of the region, one of the most industrialized in the country.

The worst hit town was Sant'Agostino, whose municipality was demolished and historic buildings were damaged.

One five-year-old girl was rescued after getting trapped in debris, a police officer said.

Authorities instructed residents not to get close to historic buildings, while the elderly and seriously ill were rushed to hospitals as a precaution.

In 2009, an earthquake of magnitude 6.3 killed nearly 300 people in the central city of L'Aquila.