The 5.9-magnitude quake which struck around 0730 IST in the Emilia-Romagna region and the area around Venice had its epicentre 36 kilometres north of Bologna at a depth of 10 kilometres.
It lasted around 20 seconds and was followed by several aftershocks. Earlier another 4.1-magnitude quake was felt in the Lombardy region around Milan, Italy's financial and business capital.
Rescue services said the three people died on night shifts in the Modena and Ferrara areas. One man died when the workshop of a plastic-producing factory collapsed near Ferrara and the two others in a ceramics factory.
Two people were injured in another region. Several church steeples also partly collapsed and hospitals were evacuated as a precautionary measure.