Italian authorities say three sisters have died after their camper burst into flames as they slept on Rome's outskirts.

Prosecutors are investigating the cause of the blaze early Wednesday in the Centocelle neighborhood.

The ANSA news agency said the sisters were aged 4, 8 and 20, and were Gypsies, also known as Roma. It said other family members managed to escape.

Rome police Cmdr. Mario De Sclavis said the victims weren't well known to area residents, who reported hearing a huge explosion followed by screams.

Mayor Virginia Raggi visited the site of the blaze Wednesday and asked for a moment of silence.