A bomb exploded at a migrant shelter in Sardinia on Thursday after it as left by a side door of the building in Dorgali in the province of Nuoro, police said.
The bomb went off at around 2.30 am at the shelter, where 64 migrants and two workers from a cooperative that runs the centre were asleep inside.
The powerful blast blew off the side door to the shelter and could have hit some of the migrants who were sleeping just metres away, police said.
Two 23-year-old Nigerian residents at the shelter sustained bruises as they clambered out of bed in a panic after the bomb went off, according to police.
The centre has no video security cameras, said police, who have opened an investigation into the attack.
Late on Tuesday, a paper bomb was hurled against an external wall of an asylum-seeker centre in Rocca di Papa, south of Rome, housing about 380 migrants, with no reports of injuries.
Police in Rocca di Papa were studying images from security cameras mounted outside nearby shops as part of a probe of the attack.
Police have not stated if they believe the attacks in Dogali and Rocca di Papa were linked.